Very fond memories of Mir Publishers' science and math books growing up in India in the 80s and 90s. I think English translations were freely available in India. My grandfather would buy them for me to encourage my interest in science and math. If I could find physical copies of those books I would buy them in a heartbeat today.
Slight digression: Russian cartoons from that era are also very interesting. One of my favorite short cartoon from that era (I still hum its music involuntarily): Ikarus and the Wise Men [0]
They only joined the UCC (Geneva Copyright Treaty) in 1973 though. That was less than twenty years before the USSR ceased to exist. All the works published in the USSR before 1973 weren't copyrighted in the West (it wasn't retroactive).
While that maybe true ( I know some folks who are reprinting them ), the translated editions from those days were all printed in USSR at Mir / Raduga / Progress presses itself. We've even had poets, writers and other luminaries from India visit Moscow for this and other things as part of cultural initiatives.
Slight digression: Russian cartoons from that era are also very interesting. One of my favorite short cartoon from that era (I still hum its music involuntarily): Ikarus and the Wise Men [0]
[0] https://www.youtube.com/watch?v=0Yk1mz23YFA