Hicks, Herbert G., author
McGraw-Hill, 1976
Buku Teks
Gibson, James L., author
Irwin, 1997
Buku Teks
edited by Linda L. Putnam, Michael E. Pacanowsky
Sage, 1983
Buku Teks
Stewart, Rosemary, author
Macmillan, 1993
Buku Teks
Douma, Sytse
Prentice-Hall, 2002
Buku Teks