Schramm, Wilbur
Standford University Press, 1961
Buku Teks SO
Stefferud, Alfred
United States. Government Printing Office, 1966
Buku Referensi
Wood, Julia T., 1950-
Wadsworth and Cengage Learning, 2012
Buku Teks SO
Kothari, Ashish M.
Universities Press, 2007
Buku Teks
Maxwell, Rhoda J.
Allyn and Bacon, 1999
Buku Teks SO