University of Queensland, 1968
Buku Teks
Saye, Albert B.
Prentice-Hall, 1966
Buku Teks
Spann, R. N.
V.C.N. Blight, 1973
Buku Teks
Hughes, Colin Anfield
Oxford University Press, 1976
Buku Teks
Walker, Edward Everett, 1900-1974
Charles Scribner's Sons, 1943
Buku Teks