Mepụta ụdị dị mgbagwoju anya nke ahịrịokwu a Ndị Russia demographers E.M. Andreev, L.E. Darski na T.L. Kharkova (ADK) dere nyocha nke ndị Soviet site na 1922 - 1991 nke ndị Russian Academy of Science bipụtara na 1993.
N'ezie, ụdị okwu dị mgbagwoju anya nke ahịrịokwu ahụ bụ "ndị Russia demographers E.M. Andreev, L.E. Darski na T. L. Kharkova (ADK) dere ọmụmụ banyere ndị Soviet site na 1922 - 1991 nke ndị Russian Academy of Science bipụtara na 1993 mere atụmatụ ngụkọta ndị Soviet funahụrụ nde mmadụ 26.6 n'agha ahụ. "