Jary, David
Harper Collins, 1991
Buku Teks SO
Theodorson, George A.
Barnes & Noble Books, 1969
Buku Referensi
Oxford University Press , 1994
Buku Referensi
Calhoun, Craig J.
McGraw-Hill , 1994
Buku Teks
Farley, John E.
Prentice-Hall, 1992
Buku Teks SO