Gelfand, M.A.
Unesco, 1971
Buku Teks SO
Sommerlad, E.Lloyd
University Press, 1966
Buku Teks SO
Myint, Hla
Hutchinson University Library, 1973
Buku Teks SO
Jha, Raghbendra
Routledge, 1994
Buku Teks SO
Edited by Wilbert E. Moore and Neil J. Smelser.
Prentice-Hall, 1966
Buku Teks SO