Artikel Jurnal
Smith, T. Lynn
J. B. Lippincott Company, 1960
Buku Teks
United Nations Fund for Population Activities, 1985
Buku Teks
Malthus, Thomas
Oxford University Press, 1993
Buku Teks
edited by John F. Kantner, Lee McCaffrey
Lexington Books, 1975
Buku Referensi