European Journal of Social Sciences Studies
ISSN: 2501-8590
ISSN-L: 2501-8590
Available on-line at: www.oapub.org/soc
Volume 2 │ Issue 1 │ 2017
doi: 10.5281/zenodo.265669
EXAMINATION OF THE EMPLOYING ART OF
IRANIAN ARC AND DOME
Saaed Taheri1*, Farhad Moradi2
1
Department of Architecture, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
2
MA of Islamic Art, Tabriz Islamic Art University, Tabriz, Iran
Abstract:
The classification the types of arcs and domes in the Iranian buildings are very diverse
in terms of its geometry and efficiency. According to the primary definition, arc and
domes are a kind of ancient static system which has contributed considerable by
helping Iranian architects in order to widen and coverage openings. Regardless of the
geometric shape, factors such as the type of materials, mortar, construction technique
and the position of placement are effective in the process of arch implementation. The
persistence of these structures indicates high skill and experience of architects and the
witness of this claim are remaining arc and dome in ancient Iranian buildings that so far
has not broken under natural and human conditions. In this study, we examine the arcs
by identifying and finding out how their implementing is practiced in most historical
buildings, due to the resistance and static of these buildings. In order to analyze and
study, the present study method used executive methods to identify and introducing
examples of executive techniques in historical buildings of Iran and experimental
methods of architects, as well as books, and articles related to the topic. It can be said
that the gathering and procedures for implementation and compilation techniques, the
executive practices of these buildings are the inspiration of Iranian expert architects for
more generations and will be a good pattern for learning for those interested in this
field. Also, the executive procedures could be solution for the problems of restored
historic buildings.
Keywords: arch, dome, climate, Iranian architecture, brick arrangement
1. Introduction
The primitive humans, who firstly had not any shelter after a time settled in caves and,
with spreading their population and need for better comfort, begun to build shelter and
Copyright © The Author(s). All Rights Reserved.
© 2015 – 2017 Open Access Publishing Group
83
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
created housings with limited dimensions by embedding big stones and arranging them
on each other, forming a shelter that protected them against wild animals and even the
nature. Definitely, building bigger places have been a need of life. The primitive
humans have created initial arcs by linking stones to each other and inventing the first
arcs as well as exploring limestone.
Architecture as creating space is an issue that has been raised at the beginning of
human settlement and human has faced with various obstacles on its evolution and
development. Architecture deals with the aim of developing space and more
perspective for users. How to cover these openings has been always the problem of
architects. This kind of problem is solved in architecture different ways. Designing arc
and dome in the small and extended openings is one of the architectural approaches to
solving these problems. The oldest arch and dome in Iran comes back about the second
millennium before Christ that has used in Zanbil Ziggurat. It can be said that: ”…arcs
are curved lines that their openings are bigger than their waves” (Zamrashidi, arc and dome I
Iranian architecture)
Iran’s architecture is a source of balances, compliances and the arc and dome are
one of the basic elements of this architecture. Given that, the lack of knowledge about
materials with tensile strength, such as steel is the only method to opening way
between two arched structures that transfers the power forced on the arch to the
bearing with pressure mechanism. Architecture more than any other discipline, is
affected by the climate and art. By examining Iranian buildings can understand that
these artists have respected climate and environment more than any in other lands. The
first instruction to Iranian architectures is to follow the nature. The arc elements are one
of the parts of Iranian buildings that are aligned with the climate. It shines more in the
dry and hot climate.
2. Definitions
According to Giasaddin Jamshid Kashani arc is: a curved structure, its mouth is wider
than its depth and dome shapes from visualizing an arc in the space. In general, we can
say that the arch is a concept to cover the space between the two walls and a shape of
dome that in terms of form follows it called arc.
2.1 The terms of the vault and arches in Islamic-Iranian architecture
Vault: move of an arc along a line, the resulted line is vault.
Dome: move of an arc around a point in this environment, forms a dome
Afraz: the height of an arc or dome from the wall to the highest point
Parasti: the lower part of arc that vertically arises along the wall
Pakar: the connection point of vault or dome to the bearing wall that is built with
Toizeh method
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
84
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
Toizeh: a strip arc of bearing in vaults that are constructed with Toizeh method
Tabreh: Thickness of the arch or dome, which started from the lowest point with
greatest thickness and becomes thinner with climbing of arc
Tizeh: the highest point of the arc in the vault or domes that are built with zigzag
and Tizedar style
Khiz: the ratio of Afraz size to the mouth of a dome
Mouth: the interval between walls that are covered with vault or dome
Gaz: Pieces of bricks or tiles that fill the empty space between triangular among
the bricks or arranged bricks
Horno: a hole that is built at the top of the arch or dome for lighting and air
movement.(Pirnia, Vaults and arcs)
Ivargah:67.5 degree
Tizeh: 90 degree
Shekargah: 22.5 degree
Among the comb: 45 degree
Figure1: Elements of vault (source: Archive of author)
3. The coverage of openings is divided into two types: 1: flat .2segh (2-1 mazedar, 2-2
tizedar)
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
85
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
Figure 2: The curved vaults (source: author)
Two types of Segh can be seen in Zanbil Ziggurat.
3.1 Identification of arches
According to segmentations made by Mohammad Karim Pirnia the vaults are divided
into four categories:
A. 3-1-track arches: track arches is like a half-cylindrical arch that runs with building
materials and placed on two bearing wall and end wall of the arc like Taghe Kasra in
Biston ,the used arches in ziggurat Zanbil
Figure 3: the tomb of Ielami in
Sush museum
(the second millennium B.C)
Figure 4: Taghe Ksra or Ivan Madaen
in Tisfon (Iraq)
B. Four part Arch: If the two tracks arches vertically cut off each other, the four arches
will create from their intersection and has various types such as tent four part vault.
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
86
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
Figure 5: Four part vault
(Memarian)
Figure 6: Tent four part vault
(Memarian)
C. Vetoizeh vault: it is like a brick cylindrical that there are arc shapes inside the vault
that arecalled Toizeh and transfers the bearing of the ceiling to the wall. The beam
functions in the beat arch like Toizeh.
Figure 7: Vault and Toizeh at the north part of
the Masjedannabi
Figure 8: Sabat Toizeh of Attar
(Dezfol Pirnazar environment)
D. Klonbeh vault: to run Klonbeh vault firstly four Toizeh installed on the base of the
vault then the free space between Toizeh filled with the brick.
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
87
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
Figure 9: Run the Klonbeh vault in
Imam Ali masque in Yazd city
Figure 10: The mosque of
Khosroabad village of Garos (Bijar)
4. Connecting the arch to the lower elements
4.1 The deepen method (iron): in the section of arc starting, linking it to the pillar, the
first row of brick will be running a bit behind. The built dimple is a good place to
establish of template and thus there is no need to a base to keep the template. This
method is come back to pre-Islamic times (figure 11).
4.2. Hmbad method: In this method, the arch and the lower bearing elements are
Hmbad together. By placing wooden pillars under the form of an arch and Jerry they
become Hmbad together. This method is most common running approach; in some
cases with wooden drums with the protrusions around the pier, the place of locating
template will be provided and then it can be used as a decorative section like Masjed
Jme Hamedan, figure 12.
4.3 The protruded method: Before the finishing of the pier row run as Lariz following a
row last arc which this provide the place of locating .in this method the mouth is
smaller, figure 13.
Figure 11: (Author resource)
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
88
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
Figure 12: The south of
Ivan of Hamedan mosque
Figure 13: Hashti of
Qazvin Emamzade
5. Executive materials
A variety of building materials that usually are practical in Iran is used for the vault.
They are wall glue, brick, clay, road metal stone, cleaner stone etc. (Zamarshadi, Iranian
architecture). Different properties of these materials are causing advantages or
limitations on the run: for example, the homogeneity of the mortar to brick and helper
stone. Since this integration is created, enjoying the coordination mortar and materials.
The material properties are important in connection with mortar stiffness.
Iranian arch implement a special place because of certain circumstances. Brick and clay
have the most of adhesion volume to the plaster and stone has the lowest rate of
adherence to these mortars. Also, the way of forming these materials is considered. By
using materials such as wall glue, which itself is formless in the arc forms (arch or
dome) to complete drying is required to use templates. Wall glue is the only a part of
the set of materials that is formless and integrated and it can be formed as desired
during implementation (Tehrani, beyond the geometry of arc and dome, journal page 6
to 8).
6. Executive techniques
These techniques provide the possibility of space coverage by means of vault building
and lead to vault adherence. These techniques can be divided into two categories: 1)
ability to run without form and 2) run by means of template (Baznoal, Vault
technology, 55)
6.1 Run without template
6-1-1: image on the Esper: executive is done by a wall or the arc for vaults that have
pillars. In this case, the load-bearing wall in one of the two extremes is connected to
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
89
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
each other. This arc or the wall is higher from the height of wall bearing wall at least as
the height of dome. The generator is drawn on this arc by the mortar. If this path is not
regarded, the essential is to create a bearing surface. Bricks that make up the first vessel
of the arc, adhered on the fresh mortar and is drawn the generator arc. Then this first
vessel is considered as bearing surface for the second vessel that established with
different sections on the first vessel. In this case, progress of arch is horizontal. With the
progress of building and in each moment, the formed vault is static in comparison with
its final shape but it should be noted that this is only permissible when they used a
mortar that is very high steak (Baznaval, arc technology, 60).
Figure 14: A picture on the Esper (Sasani track arc) (source: Baznaval, arc technology, 60)
6.1.2 Jahazeh vault: The arch, which usually runs in small openings is as a transfer
restriction among ceilings and openings in fact it similar to a port brick horseshoe that
in one hand transfer the ceiling load to the opening and on the other hand prepare the
required bearing conditions for locating vault to the right corner of downstream.
Running is that firstly builder try to making exponential arch with covering layout on a
wooden port or sometimes directly among each of the sides of four wall. After some
initial vessel arranging of this arch continued by reaching to desired balance, running
the main vault is started. Lintel brick port is the same lairized vessel which transfers the
load of vault to the openings. Sometimes, in cases that covering big mouth is needed, a
vault that is run with romance layout. In this case the romance vault acts like lintel brick
and the role of covered vessels is template.
Figure 15: Jahazeh room (Bam Citadel)
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
90
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
6.2 A variety of templates: using template in implementation of arc coverings can
facilitate work for administrators as well as using it more resistant and shape that is
more regular can be obtained.
6.2.1 Straw and plaster template: in cases that there is no Ahang and fallen vault and
there is no Esper wall we required to use template. A template that is associated with
both the anchor and a bearing to start instead of Esper. Straw and plaster template has
the tolerance of low load in Iran used instead of wooden mold that after install over Jarz
and fixing it the bricks are stick to it. Straw and plaster template after implementation
remains in the work and can be a bent texture for joinery. Straw and plaster templates
are either integrated that are commonly small and sharp or leaves, not sharp and have
relatively large openings that with plaster mortar become to vault (figure, 16)
6.2.2. A plume template vault: for larger and sensitive openings instead of installing
template that is generally wooden set out to create a row with their arch and the feather
vault Ahang is created by fattening it. The room itself is a Roman arch form.
6.2.3 Dbbeh template: is a resistant wooden template that in executive phase prevents
until reaching to two double room and mostly used as romance method in order to
stone or brick vaults.
Figure 16: Mold and straw
Figure 14: Daeh template
7. Methods of arranging adobe and brick
Arranging of adobe and brick is done with two ways:
7.1 The method of vessel ordering: in this method the execution materials (clay, brick,
and stone) in comparison with previous vessel comes forward a little and all vessels are
parallel to the opening. The projection of vessels cause that the mouth becomes narrow
thus the arch becomes heavy. In this way, each vault door is stationary alone and when
the two doors reach together, their balance and stability will be added.in vessel
ordering running vault is done behind the vault. The amount of projection in this
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
91
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
method is done with view of architecture that it is effective in the height space.in this
method the rows are less Laryzed the run vault is more high and the external pressure
is reduced. Due to the implementation method, the number of buildings of vessel
ordering is less than Drochin method (figure 18)
7.2 Dorchin method: in this way, the brick angle is variable to the horizon. Bricks are
always in line with the radius of the creator arc. How to locating the bricks in the
Dorchin is with different styles such as Romance, feather, blade, cut head or a
combination of them that each containing different performance, the development
potential of forms of bearing resistance. The main Toizeh of bearer usually run with
romance method or a combination of them in two modes.in building generally to belter
control and reducing asymmetrical pressure on their vault run them as symmetrical.in
most cases laying brick is done as feather to the Toizeh. With the help of arched form,
the shape can be corrected. If the architect's diagnosis base on the pressure of load over
the template, to continue the work must use the candle to keep template and vault.
Also, the implementation path can be changed (figure 18).
Implementation with Dorchin method due to type of implementation, existence
of thickness difference of mortar on the exterior and interior part .to more homogenies
run to the Shekargah implemented as romance and feather. The difference amount of
waste mortar is considerable such that according to investigated examination if in the
section of Shekargah bricklaying run as feather thick mortar differences 6 cm and if it be
as romance method it is 1.5 cm.in the Shekargah to Tizeh if bricklaying is done with
romance mode, the difference of mortar weed would be 0.28 cm and if it be full the
thickness difference will be 1.4 cm that two figures of 1.5 and 1.14 are closer. This
method is used when there is a difference of homogeneity in the mortar emanates. If the
amount of this homogeneity is added, the architecture can apply different layouts
(Tehrani et al, 2011, 7)
Figure 18: The arrangement of adobe and brick
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
92
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
Table 1: Examining the methods of brick arrangement in the track vault
Type of brick
arrangement
Beat bricklayer
Feature
Map
- Its run is easy
-It is less durable than
Development
in
line with the room
length
the Roman style
- it is arranged more in
the middle of arc
buildings
Romance bricklayer
How to develop
the arch
Has more resistance due
to being stuck in the
vertical plane
-until Shekargah run
without template
- after running template
is run from two sides
and ends in Tizeh
- the thickness of brick
forms the thickness of
arc
- it used more for
balancing of the arc
Develop in line of
room width
Used for decoration low
parts of the room
Development in the
diagonal
line(45
degree)
It is used for the arch
resistant against
buoyancy forces
- the romance bricklayer
to the Shekargah and
from then beat
bricklayer is used
Source: Fakhar Tehrani article
A bricklayer on a perpendicular arc, the romance and
blade bricklayer in line with the arc has run
development such that how to implement bricklayer
with how to develop it makes 90 degree angle.
Chbile bricklayer
Sleeping bricklayer
orders
Combined bricklayer
(romance,
beat,
blade)
Develop in line of
room width
8. Review mechanism of arches
Since many traditional building materials such as stone and brick despite resistance
suits against compressive stress, have little ability to withstand tensile stress .the arc
design of the vault could be very useful. In an arch, a large section of the vertical load
without bending moment and therefore no member of the arch will not be under tensile
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
93
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
stress. However, what about vaults may be complex, the tensile stress is the stress
arising from buoyancy forces. This driving force that is always in the horizontal and
outward pressure on both sides of the arch where the arch sits peak on the walls of the
anchor that this can be breaking in the big arcs this problem with these methods is well
solved.
8.1 Add the curvature of the arc (rising more prone of the arch): This method is an
efficient way to reducing and even full removing of driving force. Since with more mast
deflection and curvature the arch more arcs, horizontal buoyancy forces are gradually
being replaced by vertical compressive forces. Further, sharpen the arch to strengthen
its stability against the stresses thrust takes place in a horizontal orientation. However,
this method has some limitations and it is adding to the weight of the building due to
rising of the vault that it is possible that increasing pressure on the entire overhead
structures. However, the remedy for this problem and it is thought to reduce the
thickness or pier the arch with each Reggie Tabreh that the stigma (the tip of the arch)
goes up. As with the arch to last row, Tabreh may be only the size of the slim narrowest
section of a brick. Another limitation is that the longer the arch structural engineering
and aesthetic arguments beyond its structure and attractive returns. It discusses in
particular the traditional architecture of the building fits under the popular principle
which has long been highly regarded architectural Iran. What structures that is too long
may be unpleasant and distress viewers and passersby. Perhaps for this reason that the
vault with arc has long been used in water reservoirs. That half of the water storage
structures are placed in the ground and this is a reduced height of self. (Pirnia,Vaults
and arcs, Cultural Heritage).
8.2 Adding the thickness of the Jarz: in this method the walls that have the role of the
support are made thicker that this helps, stability of the wall to be against arch thrust
pressures. The thickness varies depending on the type of building materials that its
sizes have been measured and gathered. For example the minimum of jarz for a 35 cm
wall (equal to 5 g) and for a brick wall 80 cm (equal to 12 gr) to create a necessary
resistance. In this size as the curvature of arc becomes less and the arc close to smoothly
line that followed by increasing driving force it should for occurred tension the
thickness of the Jarz be added until the resistance established by this way the vaults will
built with less curvature. With fact that arc at the least amount of deflection transfers
the most driving force to the walls and this increasing force requires the most thickness
force for containment. Just why that the less curvature arcs that are called Kafteh are
used always in Eshkobs that are Low Floor coverings Structures since the most Jarz is in
the lower floors of the building. In the construction of bridges and dams as mountain or
lumbar is the support that has the function of Jarz with the best method can use arcs
with the less curvature. However, the curvature usually does not exceed a certain
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
94
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
proportion. When arcs closer to the straight line that brings unpleasant vibrations in
structures. These vibrations in the flat coverage’s becomes high that is one of the less
chance to flat coverage’s in Iranian architecture despite using powerful beams to more
consistent of the same objection tremor.
9. Regional correlation of arc and vault; since the emergence and development of
these architectural elements used more in climates
These forms, comply not only with materials and structural reasons, but in addition to
having thermo physical reasons. It is also appropriate to reduce heat transfer. Firstly,
because they are spherical convex shape is perfectly suited to emit thermal radiation
and makes it easier becoming it cool during night. Secondly, during the day and during
the morning and afternoon a half of the dome is in the shadow of the other half and this
is plays an important role in reducing roof temperature. Also, domed roof due to the
raised is being exposed to the wind and therefore heat leaves less effect on it.
a. Building ceilings higher than usual: Warmer air moves upward and inward fresh air
enters the lower openings and this issue is caused air moving ,arch height can be
expressed this issue.
b. Building double ceilings: the temperature capacity of air is very low and equals to
BTU/F 0.018 and the air between the two shell acts as a thermal insulator and, therefore,
less heat is transferred into the inside and in summer, the inner shell will be cooler than
the outer layer (figure 19).
Figure 19: The impact of climate on vault elements
(Yazd Jame masque, double shell dome)
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
95
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
10. Conclusion
In this paper, the process of architectures skills in building arc and vault as well as
inventing such buildings and running them from the first to the end examined .
Certainly, considering experiences of predecessors and studying them always will lead
to the discovery of artistic facts. Examining all types of the vaults and these covering
elements according to verity and expanding Iranian vaults is out of the scope of this
study but the result of such a study, to learn the skill and accuracy of modern
architecture from the skill and accuracy of past architectures. Although these
techniques of predecessors, today is outdated in the building however, the result of a
new building using today's modern technology, is bound to observe the notes of these
artists so that today, fortunately, in most views, bridges, our new buildings still see
traditional arch and vaults. No doubt to show an Iranian architecture and separating it
from the modern world we need to use these elements. The result of this research could
be a guide for the correct application of contemporary buildings or for rebuilding arch
of historical buildings.
References
1. Banzoal, Rolan, 2015, Technology of arc and vault in ancient east ,translation of
Saed Mohsen Habibi, first publication, Tehran, Cultural Heritage Organization.
2. Pirnia, Mohammad Karim, 2003, Style architecture of Iran, Tehran, Soroush
Publications knowledge
3. Pirnia, Mohammad Karim, 1993, ”Arcs and vaults”, compilation of Zohreh
Bozorgmehri, Asar journal, number 24, Tehran, Cultural Heritage Organization
4. Zamrashidi, Hossein, 2004. Implementation of building with traditional
materials, Sixth Edition, Tehran, Azadeh Press
5. Zamrashidi, Hossein, 1993, Arch and vault in Iran's architecture, printing,
Tehran, Kaihan publication
6. Fakhar Tehran, Farhad, 1993, "Beyond the arch and dome geometry” general
magazine; the second, 6 to 8.
7. Kashani, Giasaddin Jamshid (1193 AH); vault treatise, translated by Alireza
absorption, Tehran, Soroush Publications
8. Memarian, G. H, 2012, Iranian architecture; Niaresh, Volume I; First Edition,
Tehran, Press N. forward thinking
9. Memarian, G. H.; 1995; Niaresh arched structures in Iran, Tehran, University of
Science and Technology
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
96
Saaed Taheri, Farhad Moradi
EXAMINATION OF THE EMPLOYING ART OF IRANIAN ARC AND DOME
10. Fkharthrany, Farhad and Hamkar; 2013; establishing effective enforcement
techniques in promoting arch resistance; Journal of architectural ideas; the first
year; the first issue
11. Pirnia, Mohammad Karim, 1992; dome architecture of Iran, the magazine works,
issue of, published by the Cultural Heritage Organization
12. Perna, M., 2008; Master restoration revival of historical monuments of tissue and
release free.
Creative Commons licensing terms
Author(s) will retain the copyright of their published articles agreeing that a Creative Commons Attribution 4.0 International License (CC BY 4.0) terms
will be applied to their work. Under the terms of this license, no permission is required from the author(s) or publisher for members of the community
to copy, distribute, transmit or adapt the article content, providing a proper, prominent and unambiguous attribution to the authors in a manner that
makes clear that the materials are being reused under permission of a Creative Commons License. Views, opinions and conclusions expressed in this
research article are views, opinions and conclusions of the author(s). Open Access Publishing Group and European Journal of Social Sciences Studies
shall not be responsible or answerable for any loss, damage or liability caused in relation to/arising out of conflicts of interest, copyright violations and
inappropriate or inaccurate use of any kind content related or integrated into the research work. All the published works are meeting the Open Access
Publishing requirements and can be freely accessed, shared, modified, distributed and used in educational, commercial and non-commercial purposes
under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
European Journal of Social Sciences Studies - Volume 2 │ Issue 1 │ 2017
97