Bennett, A. Gordon
Gloucester, Mass, 1980
Buku Teks
Good, Yohn M
Heath, 1970
Buku Teks
Christenson, Reo M.
Harper & Row Publishers, 1982
Buku Teks
LeBlanc, Robin M
University of California Press, 1999
Buku Teks
Harmon, M. Judd
McGraw-Hill, 1964
Buku Teks