Quine, Maria Sophia
Routledge, 1996
Buku Teks
Cronin, James E., author
Routledge, 1991
Buku Teks
Robbins, Lionel, author
Macmillan, 1954
Buku Teks
Population Institute East-West Center, 1987
Majalah, Jurnal, Buletin
Agarwala, S. N.
Tata McGraw-Hill, 1977
Buku Teks