Dawe, Jessamon, author
Prentice-Hall, 1974
Buku Teks
Holt, Rinehart and Winston of Canada, Limited, 1988
Buku Teks
Shurter, Robert L.
McGraw-Hill, 1957
Buku Teks
Treece, Malra, author
Allyn and Bacon, 1989
Buku Teks
Ewald, Helen Rothschild, author
Prentice-Hall International, 1997
Buku Teks