Herriott, Luke, author
Rockport, [date of publication not identified]
Buku Teks
Herriott, Luke
Rockport publishers, Inc., 2009
Buku Referensi
Fakultas Filsafat Universitas Katolik Santo Thomas, 2002
Majalah, Jurnal, Buletin
Farrelly, Lorraine, author
Wiley-Academy, 2003
Buku Teks SO
Sussman, Art, author
Jossey-Bass , 2006
Buku Referensi