Especially weird when you remember that BT-42 was developed in Finland. And only 18 were ever produced. I cannot imagine who in the world may need this manual in Ukrainian of all languages. The cover should be something like "Rynnäkkötykki BT-42" at the very least.
Russian, Polish, and Ukrainian military history publications are a big thing right now on a whole number of topics from ships, to planes, to tanks, to just guns. From most of the 20th century. A friend of mine got a large number of Russian books on various ships involved in the Russo-Japanese War. He can't read them, but got them anyway as they have pictures and drawings that aren't in Western publications.