Hydrocarbon Processing - April 2022 - 59
Industry Pioneers
Phillips Petroleum was involved in concerted efforts to investigate
the uses of natural gas liquids (NGLs). Hogan and
Banks were studying processes by which propylene and ethylene
could be converted to valuable gasoline-like materials,
so they started investigating the use of catalysts to do so.
In June 1951, they were experimenting by adding a small
amount of chromium oxide to a nickel oxide catalyst and fed
propylene with a propane carrier through the catalyst-packed
tube. While pure nickel oxide yielded the expected product
of low-molecular weight hydrocarbons, the chromium-modified
catalyst produced a white solid-a new material, crystalline
PP. With this new discovery, they pivoted research
efforts from gasoline to plastics and used the chromium catalyst
to produce an ethylene polymer. Within a year, they created
the process for making HDPE-the safest, hardest and
most heat-resistant plastic created at the time using much
lower operating pressure than branched low-density PE.
Phillips launched their product as Marlex® in 1954.7
Their
invention revolutionized the consumer plastics industry and
launched Phillips, an oil company, as a manufacturer of polyolefin
plastics. HDPE is extensively used in packaging, commodity
plastics, toys, tools, furniture, auto parts and a variety
of other applications.
Hogan received the Pioneer Chemist Award and is credited
with 52 U.S. patents.8
Hogan and Banks together received the
Perkin Medal in 1987, the Heroes of Chemistry award by the
American Chemical Society in 1989 and were inducted into
the National Inventors Hall of Fame in 2001.9
KARL ZIEGLER
In 1953, German chemist Karl Ziegler
employed a catalyst consisting of a
mixture of titanium tetrachloride and
an alkyl derivative of aluminum to create
a high molecular weight, high melting
point and straight-chain PE. His
pioneering research with organometallic
compounds, which made industrial
production of high-quality PE possible,
won him the 1963 Nobel Prize in Chemistry, which he
shared with Giulio Natta.10
Ziegler's research established new polymerization reactions;
enabled the syntheses of durable, higher melting,
unbranched polymers; and laid the groundwork for several
useful industrial processes. He combined classical organic
chemistry with physical and analytical experimental methods
in his phenomenal work on polymerization reactions.
Ziegler began his work on carbon compounds and organometallic
chemistry during his professorship at the
University of Heidelberg, which he continued after joining
as the Director of the Max-Planck-Institut in Mülheim
in 1943.11
Between 1952 and 1953, Ziegler's research group
tested various organoaluminium compounds and discovered
that nickel was the cause of the chain-ending reaction. They
further investigated to find a reagent to suppress this chain
termination reaction, which led them to discover that titanium,
under mild atmospheric conditions, produced rigid,
high-melting unbranched PE.
Besides his work with organometallic compounds, he is
also known for his research in the field of radicals with trivalent
carbon and synthesis of multi-membered ring systems,
which earned him the Liebig medal in 1935.11
One of the
many awards Ziegler received was the reputed Werner von
Siemens Ring in 1960 for expanding the scientific knowledge
of and the technical development of new synthetic materials.10
Ziegler
was able to take his discovery to industrial markets.
By 1958, he was reaping the benefits of approximately
two dozen licenses.12
GIULIO NATTA
Giulio Natta, an Italian scientist and
chemical engineer, extended Ziegler's
method to other olefins. Based on his
own findings on the reaction mechanism
of polymerization, he developed
further variations of the Ziegler catalyst.
For his contribution to the field of high
polymers, he shared the Nobel Prize in
Chemistry with Karl Ziegler in 1963.13
Commercial Ziegler-Natta catalysts include many mixtures of
halides of transition metals, especially titanium, chromium,
vanadium and zirconium, with organic derivatives of nontransition
metals, particularly alkyl aluminum compounds.14
Natta's early research career focused on studying solids
by x-rays diffraction (XRD) and electron diffraction. He
later employed the same expertise to study catalysts and the
structure of high organic polymers. By 1938, he began investigating
macromolecules-polymerization of olefins and the
kinetics of subsequent concurrent reactions.15
In 1953, after
he received financial aid from the large Italian chemical company
Montecatini, he extended Ziegler's research on organometallic
catalysts to stereospecific polymerization.15
These
studies led to the development of isotactic PP, a thermoplastic
polymer of highly regular molecular structure with commercially
important properties of high strength and a high melting
point. In 1957, Montecatini produced this polymer on an
industrial scale at their Ferrara plant.15
Natta's creation was
commercially marketed as a plastic material by the name of
Moplen, as a synthetic fiber by the name of Meraklon, as a
monofilament by the name of Merakrin, and as packing film
by the name of Moplefan.15
Natta discovered new classes of polymers and used XRD to
determine the exact arrangement of chains in the lattice of the
new crystalline polymers he discovered. He created polymers
with sterically ordered structure-isotactic, syndiotactic and
di-isotactic polymers and linear nonbranched olefinic polymers
and copolymers with an atactic structure.
Natta is also known for his later research that led to two
different routes for the synthesis of new elastomers: by polymerization
of butadiene into cis-1,4 polymers with a high degree
of steric purity, and by copolymerization of ethylene with
other a-olefins (propylene), originating extremely interesting
materials such as saturated synthetic rubbers. Natta published
700 research papers of which about 500 focus on stereoregular
polymers. He also received several awards and has many patents
in different countries to his credit.15
Hydrocarbon Processing | APRIL 2022 59
Hydrocarbon Processing - April 2022
Table of Contents for the Digital Edition of Hydrocarbon Processing - April 2022
Contents
Hydrocarbon Processing - April 2022 - Cover1
Hydrocarbon Processing - April 2022 - Cover2
Hydrocarbon Processing - April 2022 - Contents
Hydrocarbon Processing - April 2022 - 4
Hydrocarbon Processing - April 2022 - 5
Hydrocarbon Processing - April 2022 - 6
Hydrocarbon Processing - April 2022 - 7
Hydrocarbon Processing - April 2022 - 8
Hydrocarbon Processing - April 2022 - 9
Hydrocarbon Processing - April 2022 - 10
Hydrocarbon Processing - April 2022 - 11
Hydrocarbon Processing - April 2022 - 12
Hydrocarbon Processing - April 2022 - 13
Hydrocarbon Processing - April 2022 - 14
Hydrocarbon Processing - April 2022 - 15
Hydrocarbon Processing - April 2022 - 16
Hydrocarbon Processing - April 2022 - 17
Hydrocarbon Processing - April 2022 - 18
Hydrocarbon Processing - April 2022 - 19
Hydrocarbon Processing - April 2022 - 20
Hydrocarbon Processing - April 2022 - 21
Hydrocarbon Processing - April 2022 - 22
Hydrocarbon Processing - April 2022 - 23
Hydrocarbon Processing - April 2022 - 24
Hydrocarbon Processing - April 2022 - 25
Hydrocarbon Processing - April 2022 - 26
Hydrocarbon Processing - April 2022 - 27
Hydrocarbon Processing - April 2022 - 28
Hydrocarbon Processing - April 2022 - 29
Hydrocarbon Processing - April 2022 - 30
Hydrocarbon Processing - April 2022 - 31
Hydrocarbon Processing - April 2022 - 32
Hydrocarbon Processing - April 2022 - 33
Hydrocarbon Processing - April 2022 - 34
Hydrocarbon Processing - April 2022 - 35
Hydrocarbon Processing - April 2022 - 36
Hydrocarbon Processing - April 2022 - 37
Hydrocarbon Processing - April 2022 - 38
Hydrocarbon Processing - April 2022 - 39
Hydrocarbon Processing - April 2022 - 40
Hydrocarbon Processing - April 2022 - 41
Hydrocarbon Processing - April 2022 - 42
Hydrocarbon Processing - April 2022 - 43
Hydrocarbon Processing - April 2022 - 44
Hydrocarbon Processing - April 2022 - 45
Hydrocarbon Processing - April 2022 - 46
Hydrocarbon Processing - April 2022 - 47
Hydrocarbon Processing - April 2022 - 48
Hydrocarbon Processing - April 2022 - 49
Hydrocarbon Processing - April 2022 - 50
Hydrocarbon Processing - April 2022 - 51
Hydrocarbon Processing - April 2022 - 52
Hydrocarbon Processing - April 2022 - 53
Hydrocarbon Processing - April 2022 - 54
Hydrocarbon Processing - April 2022 - 55
Hydrocarbon Processing - April 2022 - 56
Hydrocarbon Processing - April 2022 - 57
Hydrocarbon Processing - April 2022 - 58
Hydrocarbon Processing - April 2022 - 59
Hydrocarbon Processing - April 2022 - 60
Hydrocarbon Processing - April 2022 - 61
Hydrocarbon Processing - April 2022 - 62
Hydrocarbon Processing - April 2022 - 63
Hydrocarbon Processing - April 2022 - 64
Hydrocarbon Processing - April 2022 - 65
Hydrocarbon Processing - April 2022 - 66
Hydrocarbon Processing - April 2022 - 67
Hydrocarbon Processing - April 2022 - 68
Hydrocarbon Processing - April 2022 - 69
Hydrocarbon Processing - April 2022 - 70
Hydrocarbon Processing - April 2022 - 71
Hydrocarbon Processing - April 2022 - 72
Hydrocarbon Processing - April 2022 - 73
Hydrocarbon Processing - April 2022 - 74
Hydrocarbon Processing - April 2022 - 75
Hydrocarbon Processing - April 2022 - 76
Hydrocarbon Processing - April 2022 - 77
Hydrocarbon Processing - April 2022 - 78
Hydrocarbon Processing - April 2022 - 79
Hydrocarbon Processing - April 2022 - 80
Hydrocarbon Processing - April 2022 - 81
Hydrocarbon Processing - April 2022 - 82
Hydrocarbon Processing - April 2022 - 83
Hydrocarbon Processing - April 2022 - 84
Hydrocarbon Processing - April 2022 - 85
Hydrocarbon Processing - April 2022 - 86
Hydrocarbon Processing - April 2022 - 87
Hydrocarbon Processing - April 2022 - 88
Hydrocarbon Processing - April 2022 - 88A
Hydrocarbon Processing - April 2022 - 88B
Hydrocarbon Processing - April 2022 - 89
Hydrocarbon Processing - April 2022 - 90
Hydrocarbon Processing - April 2022 - Cover3
Hydrocarbon Processing - April 2022 - Cover4
Hydrocarbon Processing - April 2022 - GP-1
Hydrocarbon Processing - April 2022 - GP-2
Hydrocarbon Processing - April 2022 - GP-3
Hydrocarbon Processing - April 2022 - GP-4
Hydrocarbon Processing - April 2022 - GP-5
Hydrocarbon Processing - April 2022 - GP-6
Hydrocarbon Processing - April 2022 - GP-7
Hydrocarbon Processing - April 2022 - GP-8
Hydrocarbon Processing - April 2022 - GP-9
Hydrocarbon Processing - April 2022 - GP-10
Hydrocarbon Processing - April 2022 - GP-11
Hydrocarbon Processing - April 2022 - GP-12
Hydrocarbon Processing - April 2022 - GP-13
Hydrocarbon Processing - April 2022 - GP-14
Hydrocarbon Processing - April 2022 - GP-15
Hydrocarbon Processing - April 2022 - GP-16
Hydrocarbon Processing - April 2022 - GP-17
Hydrocarbon Processing - April 2022 - GP-18
Hydrocarbon Processing - April 2022 - GP-19
Hydrocarbon Processing - April 2022 - GP-20
Hydrocarbon Processing - April 2022 - GP-21
Hydrocarbon Processing - April 2022 - GP-22
Hydrocarbon Processing - April 2022 - GP-23
Hydrocarbon Processing - April 2022 - GP-24
Hydrocarbon Processing - April 2022 - GP-25
Hydrocarbon Processing - April 2022 - GP-26
Hydrocarbon Processing - April 2022 - GP-27
Hydrocarbon Processing - April 2022 - GP-28
Hydrocarbon Processing - April 2022 - GP-29
Hydrocarbon Processing - April 2022 - GP-30
Hydrocarbon Processing - April 2022 - GP-31
Hydrocarbon Processing - April 2022 - GP-32
Hydrocarbon Processing - April 2022 - GP-33
Hydrocarbon Processing - April 2022 - GP-34
Hydrocarbon Processing - April 2022 - GP-35
Hydrocarbon Processing - April 2022 - GP-36
Hydrocarbon Processing - April 2022 - GP-37
Hydrocarbon Processing - April 2022 - GP-38
Hydrocarbon Processing - April 2022 - GP-39
Hydrocarbon Processing - April 2022 - GP-40
Hydrocarbon Processing - April 2022 - GP-41
Hydrocarbon Processing - April 2022 - GP-42
Hydrocarbon Processing - April 2022 - GP-43
Hydrocarbon Processing - April 2022 - GP-44
https://www.nxtbook.com/gulfenergyinfo/gulfpub/HPI-Market-Data-2023-v3
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2024-v2
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2024
https://www.nxtbook.com/gulfenergyinfo/gulfpub/gas-processes-handbook-2022_v2
https://www.nxtbook.com/gulfenergyinfo/gulfpub/gas-processes-handbook-2022
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hp_202212
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2023-v2
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2023
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hp_202211
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202210
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202209
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202208
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202207_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202207
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202206_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202206
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202205_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202205
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202204_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202204
https://www.nxtbook.com/nxtbooks/gulfpub/hp_032022
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202203
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202202
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202201
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202112
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202111
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202110
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2022_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2022
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202109
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202108
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_processes_handbook_2021_v2
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_processes_handbook_2021
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202107
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202106
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202105
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202104
https://www.nxtbook.com/nxtbooks/gulfpub/hp_ebooks
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202103
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202102
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202101
https://www.nxtbook.com/nxtbooks/gulfpub/catalyst_handbook_2020_v2
https://www.nxtbook.com/nxtbooks/gulfpub/catalyst_handbook_2020
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202012
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202011
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202010
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2021
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202009
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202008
https://www.nxtbook.com/nxtbooks/gulfpub/refining_processes_handbook_2020
https://www.nxtbook.com/nxtbooks/gulfpub/refining_processes_handbook_2020_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202007
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202006
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202005
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202004
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202003
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202002
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202001
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201912
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201911
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2020_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2020
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201910
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201909
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201908
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201907
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201906
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201905
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201904
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201903
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201902
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201901
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_2018_v2
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_2018
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201812
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2019_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2019
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201811
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201810
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201809
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201808
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201807
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201806
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201805
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201804
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201803
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201802
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201801
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201712
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201711
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201710
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201709
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201708
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201707
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201706
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201705
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201704
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201703
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201702
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201701
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2017mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201612
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201611
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201610
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201609
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201608
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201607
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201606
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201605
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201604
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201603
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201602
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201601
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201512
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201511
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201510
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2016mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201509
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201508
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201507
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2015tmsd
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201506
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201505
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201504
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201503
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201502
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201501
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201412
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201411
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2015mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201410
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201409
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201408
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201407
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014petrochemicalprocesses_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014petrochemicalprocesses
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201406
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201405
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201404
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201403
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014calendar
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201402
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201401
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201312
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201311
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201310
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201309
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201308
https://www.nxtbook.com/nxtbooks/gulfpub/hp_srsguide2013
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201307
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201306
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201305
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201304
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201303
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201302
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201301
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201212
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201211
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201210
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201209
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201208
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201207
https://www.nxtbook.com/nxtbooks/gulfpub/hp_srsguide2012
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201206
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201205
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201204
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201203
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201202
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201201
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201112
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201111
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201110
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201109
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201108
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201107_srsguide
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201107
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201106
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201105
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201104
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201103
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201102
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201101
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201012
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201011
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201010
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201009
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201008
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201007
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201006
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201005
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201004
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201003
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201002
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201001
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200912
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200911
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200910
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200909
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200908
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200907
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200906
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200905
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200904
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200903
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200902
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200901
https://www.nxtbookmedia.com