00507naa#a2200169#i#450# EN\\bibl\10608 20240717191947.3 1999-9836 20151217b2015####ek#y0engy0150####ca RUS RU Migration As a Factor in Leveling Socio-Economic Differentiation of Russia’s Regions Journal article Moscow All-Russian center of living standards 2015 8 с. Journal article local Shichkin I. naukaru.ru