It was the most interesting source from the genealogical point of view, because it showed not only names and ages of all the family members, but their religion, address, native tongue, occupation, birth place, and if they were literate or not. But all the primary information was in the application forms of the Census. According to Soviet Law, all such papers were to be destroyed as soon as the next census took place. So, almost all the records were destroyed in 1927, when the 1st All Soviet Union Census occurred. There are only very few documents for Grodno and Vitebsk Provinces.
Secondary sources form huge mass of different documents.
However, I'd like tell about some of them. In fact, they show not only the family name in correlation with the place. A voter list is some sort of index for real estate and business records of the settlement. Of course, you can not find any ages or other personal information there, but there is a chance to get some interesting facts from the family history. The corresponding business and real estate records for that period are also in the same archives.