edited by Bruce W. Burkhart and Wesley S. Thompson
Burgess Publishing, 1972
Buku Teks
Norstog, Knut
Northern Illinois University, 1969
Buku Teks
Deason, Temp R.
Burgess, 1968
Buku Teks
Oborne, David J.
John Wiley & Sons, 1995
Buku Teks
Bridger, R.S.
McGraw-Hill, 1995
Buku Teks