Keyfitz, N., & Flieger, W. (1971). Population: Facts and methods of demography. W.H. Freeman.
Lua i Stíl Chicago (17ú heag.)Keyfitz, Nathan, agus Willhelm Flieger. Population: Facts and Methods of Demography. San Francisco: W.H. Freeman, 1971.
Lua MLA (9ú heag.)Keyfitz, Nathan, agus Willhelm Flieger. Population: Facts and Methods of Demography. W.H. Freeman, 1971.
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