Conway-Rutkowski, Barbara lang
Mosby , 1982
Buku Teks
Owen, Mark
Houghton Mifflin, 1984
Buku Teks
Highsaw, Robert B.
Thomas Y. Crowell Company, 1954
Buku Teks
Haynes, Robert J.
George Allen and Unwin, 1980
Buku Teks
Dawson, Robert MacGregor
Vancouver The Copp Clark Publshing Co. 1957,
Buku Teks