Kirby, David K., author
Gale Research, 1975
Buku Referensi
Keaveney, Sydney Starr, author
Gale Research Co., 1974
Buku Teks
edited by Paula Geyh
Cambridge University Press, 2017
Buku Teks
Duke University Press,
Majalah, Jurnal, Buletin
Wachner, Clarence W., author
Macmillan, 1963
Buku Teks