Westoby, Adam
Free Press, 1989
Buku Teks SO
Schwartz, Benjamin
Harvard University Press, 1952, 1961
Buku Teks
Schwartz, Benjamin
Harper Torchbooks and The Academy Library, 1967
Buku Teks
Houn, Franklin W.
Prenrice-Hall , 1973
Buku Teks
Brandt, Conrad
George Allen and Unwin, 1959
Buku Teks SO