The process of stratification : trends and analyses 2026-02-15T19:49:45+03:00 DEBUG: VuFind\ILS\Driver\Folio: Token taken from global cache: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiO... - Hauser, Robert Mason; Featherman, David L. (Studies in population, 1977)