Whittlesey, Charles R., author
Macmillan, 1954
Buku Teks
Ritter, Lawrence S., author
Basic Books, 1974
Buku Teks
Black, Tyrone
Business Publications, Inc., 1981
Buku Teks
Kamerschen, David R., author
South-Western Publishing, 1992
Buku Teks
Chandler, Lester Vernon, 1905-, author
Harper & Row , 1959-1973
Buku Teks