I'm doing a research with FIR Ho Chi Minh (formerly named FIR Saigon).
I've read a document which said:
During the Fall of Saigon, ICAO, in 28th of April 1975, had divided FIR Saigon into 3 AOR: Bangkok, Singapore and Hongkong, then they gave these AOR to the corresponded FIR.
In the 7th of December, 1994, ICAO sent AOR Bangkok and AOR Singapore back to FIR Ho-Chi-Minh.
In the 1st of November, 2001, ICAO gave part of AOR Hongkong to FIR Ho-Chi-Minh, and created AOR Sanya from the remained part of AOR Hongkong.
In the 8th of June, 2006, ICAO changed AOR Sanya to FIR Sanya
I managed to search those old FIR maps in the internet but no luck for me.
Hence, I would like to find out all historical FIR maps to make a comparison.
If it is impossible to find all FIR maps, old FIR maps of South East Asia FIR is greatly appreciated.