Whitaker, Carl A.
The Blakiston Company, 1953
Buku Teks
Iversen, Carl
Levin & Munksgaard, 1936
Buku Teks
Taylor, Carl C., author
Loisiana University Press , 1948
Buku Teks
Moriarity, Shane, author
Harper & Row, 1987
Buku Teks
Guelzo, Carl M.
Prentica-Hall , 1986
Buku Teks