Wichman, Karl, author
Philadelphia, David McKay Company, 1944
Buku Referensi
edited by Judy Pearsall, Bill Trumble
Oxford University Press, 1995
Buku Referensi
Presner, Lewis A., author
John Wiley & Sons, 1991
Buku Referensi
Hibberd, James Shirley, author
Groombridge, 1953
Buku Teks
Chamberlin, Marry W., author
American Library Association, 1959
Buku Referensi