Plenty of research only last century was done in French, German and Russian: a friend is doing their PhD partially on the parallel development of climate scienc

Plenty of research only last century was done in French, German and Russian: a friend is doing their PhD partially on the parallel development of climate science in English and non-English published papers - especially in Russian, for Cold War reasons, lots of work never seemed to cross the language barrier and was simply duplicated (or never appeared on the other side).