Mary Kupiec Cayton, Elliott J. Gorn, Peter W. Williams, editors
Charles Scribner's Sons, 1993
Buku Referensi
McNeill, William H., author
Prentice-Hall, 1990
Buku Teks
edited by Anne Digby, Charles Feinstein and David Jenkins
Macmillan, 1992
Buku Teks
Bailey, Thomas Andrew, 1902-1983, author
D.C. Heath, 1987
Buku Referensi
edited by I. Grattan-Guinness
Routledge, 1994
Buku Referensi