Zink, Harold, author
Macmillan, 1948
Buku Teks
Walker, Edward Everett, 1900-1974, author
Charles Scribner's Sons, 1943
Buku Teks
Boyd, Anne Morris, author
H.W. Wilson, 1949
Buku Teks
Zink, Harold, author
Van Nostrand , 1963
Buku Teks
The America University, [date of publication not identified]
Buku Teks