Ogg, Frederic Austin, 1878-1951
Appleton-Century-Crofts, INC, 1952
Buku Teks
Walker, Edward Everett, 1900-1974, author
Charles Scribner's Sons, 1943
Buku Teks
edited by Nathan Glick
United Sates Information Agency, 1989
Buku Teks
Holt, Rinehart and Winston, 1961
Buku Teks
Saye, Albert B.
Prentice-Hall, 1966
Buku Teks