Greenberg, Jerald, author
Pearson, Prentice Hall, 2008
Buku Teks
ILO, 1974
Buku Teks
Mitchell, Terence R., author
McGraw-Hill Kogakusha, 1978
Buku Teks
Sims, David, author
Sage, 1993
Buku Teks
Johnson, Doyle Paul, author
Gramedia Pustaka Utama, 1994
Buku Teks