general editors Michael Orme, Susanna Graham-Jones
Penguin Group, 1989
Buku Referensi
Bansal, H.L.
B. Jain Publisher, 1989
Buku Teks SO
Clinard, Marshall B. (Marshall Barron)
Tree Press, 1966
Buku Teks SO
French, F. G.
Oxford University Press, 1947
Buku Teks SO
Kurtz, Linda Farris
Sage Publications, 1997
Buku Teks