Spellman, Frank R., author
CRC Press, 2009
Buku Referensi
Andrew A. Fisher, John E. Laing, John E. Stoeckel, John W. Townsend
Population Council, 1998
Buku Referensi
Rushton, Alan, author
Kogan Page, 2014
Buku Teks
MacDonald, Joseph A., author
McGraw-Hill, 2009
Buku Teks
Bond, Cecil J., author
McGraw-Hill, 1993
Buku Referensi