Laurel Saville, Steve Gordhan, Jodhua Berger, Sarch Dougher, editor
Page one publishing pte ltd, 2011
Buku Referensi
Thompson, Willard M.
McGraw-Hill , 1968
Buku Teks SO
Ambrose, Timothy
Routledge, 1995
Buku Teks SO
Donatelle, Rebecca J.
Allyn and Bacon , 1997
Buku Teks SO
Macionis, John J.
Prentice-Hall, 2000
Buku Teks