Hombs, Mary Ellen
ABC-Clio, 1990
Buku Teks
UNESCO, [T.th.]
Buku Teks
Heffernan, James A.W.
W.W. Norton & Company, 1986
Buku Teks
Hughes, Colin A.
Australian National University Press, 1968
Buku Teks
Emerick, Robert Henderson, author
McGraw-Hill, 1966
Buku Referensi