Butz, W. P. (1982). Demographic challenges in America's future. Rand.
Lua i Stíl Chicago (17ú heag.)Butz, William P. Demographic Challenges in America's Future. Sta. Monica, Calif: Rand, 1982.
Lua MLA (9ú heag.)Butz, William P. Demographic Challenges in America's Future. Rand, 1982.
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