Stamps, Norman L.
University of Notre Dame Press, 1957
Buku Teks
Watt, Homer A., author
Scott, Foresman and company , 1925
Buku Teks
Garrett, Mitchell B.
Appleton-Century-Crofts, , 1947
Buku Teks
Asher, Herbert B., author
The Dorsey Press, 1984
Buku Teks
Pollet, Peter, author
BZZTOH, 1992
Buku Teks