The International Encyclopaedia of Stamps was issued by IPC Magazines Ltd in 1970/71. 
It comprises of 84 weekly issues totalling 6 volumes:
Volume 1 (Aachen to Bulgaria)
Volume 2 (Bulgarian Occupation of Rumania to Errors)
Volume 3 (Ersttagsbrief to Italian Somaliland)
Volume 4 (Italy to New York Postmaster’s Stamp)
Volume 5 (New Zealand to St. Thomas)
Volume 6 (St. Thomas and Prince to Zwickau)
Additional volumes have been produced under the following topics:
Volume 7 (Story of the Past – The back cover of each issue runs a series from world archives and museums on the evolution of the world’s postal system, with large colour plates.)
Philatelic Articles (The inner front cover of each issue contains an editorial by James Mackay or short features of philatelic interest by Norman and Maurice Williams.)
A 32-page index of all of these volumes has been produced for the benefit of members and can be purchased from the Secretary at any Society meeting.