Agarwala, S. N.
Tata McGraw-Hill, 1977
Buku Teks
Population Institute East-West Center, 1987
Majalah, Jurnal, Buletin
Praeger Special Studies, 1979
Buku Teks
Salas, Rafael M., author
Pergamon Press , 1977
Buku Teks
edited by Philip M. Hauser
Prentice-Hall, 1969
Buku Teks