Hello Sark,
Thanks for your suggestion. The information is helpful. I hope that the site is back soon.
Some other resources for this area include:
T.E. Jones:
A Postal History of the Arabian Gulf Post Offices, Volume 1: Bahrain, Second Edition 2007
A Postal History of the Arabian Gulf Post Offices, Volume 2: Kuwait, Revised Edition April 2009
The Postal History of Kuwait, Volume 2: The Postal Markings, Revised Edition April 2009
A Postal History of the Arabian Gulf Post Offices, Volume 3: Oman, Reprinted March 2009
A Postal History of the Arabian Gulf Post Offices, Volume 4: Aerogrammes, Part 1 1942 to 1966, Third Edition February 2009
The above should be available directly from T.E. Jones.
The paper-bound books are invaluable for their information and pictures of the stamps and postal history.
Neil Donaldson also published an addition to his
The Postal Agencies in Eastern Arabia and the Gulf in 1994 I believe.
The Postal Agencies in Eastern Arabia and the Gulf itself was reprinted in 2008. The 1994 volume includes additions and corrections, as well as some more pictures of stamps, markings and postal history.
The site
www.philabooks.com may have some of these books.
Please feel to add more resources!
Best wishes,
AndrewG