Kolde, E.J
Lexington Books, 1974
Buku Teks
Vernon, Raymond, author
Harvard University Press, 1972
Buku Teks
Eiteman, David K., author
Mas Addison-Wesley , 1986
Buku Teks
Steiner, George A. (George Albert), 1912-, author
Macmillan, 1966
Buku Teks
Turner, Louis
Hamish Hamilton , 1970
Buku Teks