Barry Dufour ,Will Curtis
McGraw-Hill, 2011
Buku Teks
Cummings, William K., author
Springer, 2012
eBooks
Institute for Scientific co-coperation, [date of publication not identified]
Majalah, Jurnal, Buletin
Rooijakkers, Ad., author
Grasindo, 2008
Buku Teks
Weimer, Maryellen, author
Jossey-Bass , 2002
Buku Teks