Lortie, Dan C
University of Chicago Press, 1977
Buku Teks
Anthem Press, 2016
eBooks
Shultz, William J.
Prentice-Hall, 1965
Buku Teks
Means, Gardiner C.
Harper & Brothers Publishers, 1962
Buku Teks
Cohen, Morris L.
West Publishing Company, 1983
Buku Teks