Kretschmar, Robert S., Jr.
Preager, 1972
Buku Teks
Ryans, John K., author
Ohio Kent State University Press , 1974
Buku Teks
Heller, H Robert
Prentice-Hall, 1973
Buku Teks
Payer, Cheryl
Macmillan, 1975
Buku Teks
Soemitro Djojohadikusumo, author
F.W Cheshire, 1968
Buku Teks