Reid, William, 1926-, author
Facts On File Publications, 1984
Buku Teks
Nussbaum, Arthur, author
Macmillan, 1958
Buku Teks
Younger, R. M.
Victoria Hutchinson Group 1982
Buku Teks
Goldschmidt, Arthur, author
Westview Press, 1983
Buku Teks
editor Thomas C. Cochran, Wayne Andrew
Charles Scribner's Sons , 1962
Buku Referensi