Marat Nigametzianov wrote:

Celinograd (Astana) in 1969 must be +6 UTC not +5 https://www.worldtimezone.com/dst_news/dst_news_ussr-map-1970.html

Thanks, but that does not cite its sources and gives little detail. Do you have some more-specific information, such as original newspaper articles or legislation that talks about Astana/Akmola/Tselinograd/etc.? For an example of what we're looking for in Kazakhstan, please see the file 'asia' and its comment from Stepan Golosunov (2016-03-27), which cites http://adilet.zan.kz/ (this might be a good place for you to start, too). The 'asia' file is here: https://data.iana.org/time-zones/tzdb/asia Thanks.