edited by Clayton L. Thomas
P.G. Publishing, 1984
Buku Referensi
edited by Clayton L. Thomas
PG Publishing, 1990
Buku Referensi
Saunders, 2003
Buku Teks
Ida G. Dox [and others]
West Pub., 1997
Buku Referensi
Goulden, W. O.
Little, Brown, 1955
Buku Referensi