Roberts, Keith A.
Dorsey Press, 1984
Buku Teks
Benson, Leonard, author
Random House , 1968
Buku Teks
edited Scott G. Mcnall
Little, Brown, 1968
Buku Teks
Wright, Charles Robert, author
Random House, 1975
Buku Teks
edited by Scott G. McNall
Little, Brown and Company, 1968
Buku Teks