Alex you are probably familiar with the myriad of folk song collections published in the USA.   Many of those books have sections on historical songs so scholars and collectors do recognize historical songs as a specific category but it does not seem that we are as meticulous about that category as Russian scholars. You have received some good suggestions about how to pin down searches. You can also start a thread and just ask as you did with this one. Mudcat consists of members from all over the world and there are many knowledgeable and helpful people here, some with a vast general knowledge, some experts in specific fields, some who just might happen to have the information you seek, and some with an uncanny ability to find things. With such a large and diverse group of catters you don't always get agreement but you do have folk who try to get all the available information presented.

You will be a valuable asset to this forum. Welcome aboard.