Gregg, Donald C.
Allyn and Bacon, 1961
Buku Teks
Bowker, 1992
Buku Teks
Wiggins, Gary, 1943-, author
McGraw-Hill, 1991
Buku Teks
Maizell, Robert E., author
John Wiley & Sons, 1987
Buku Teks
King, G. Brooks, author
American Book Company, 1963
Buku Teks