Summers, Richard
Rinehart & Company, 1948
Buku Teks
Bendixen, Alfred, author
Wiley-Blackwell, 2010
Buku Teks
Boynton, Robert W., author
Boynton/Cook Publishers, 1992
Buku Teks
Baker, Edward Mayer, author
Christopher Publishing House, 1959
Buku Teks
Hampden, John
Penguin Books, 1939
Buku Teks