Williams, Leonard Aimslie
Elsevier, 1968
Buku Teks
Cox, William E., Jr.
John Wiley, 1979
Buku Teks SO
Havaldar, Krishna K.
Tata McGraw-Hill, 2005
Buku Teks SO
edited by Norman Hart
McGraw-Hill, 1984
Buku Teks SO
Keller, kotler
Pearson Education, Inc, 2006
Buku Teks SO