Gumilar Rusliwa Somantri, author
Universitat Bielefeld, 1995
Buku Teks
edited by Andrew Blowers, Chris Hammett and Philip Sarre
Hutchinson Educational in association with the Open University Press, 1974
Buku Teks
Gutkind, E. A.
The Free Press of Glencoe, 1963
Buku Teks
Choldin, Harvey M.
McGraw-Hill, 1985
Buku Teks
Schwab, William A.
Prentice-Hall, 1992
Buku Teks