by John W. McConnell [and others]
Scottforesman , 1990
Buku Teks
Blum, Walter J., author
University of Chicago Press, 1953
Buku Teks
Cambridge Harvard University Press 1962,
Buku Teks
Universatas Indonesia, 2009
Majalah, Jurnal, Buletin
Bob Perry
Sense, 2012
eBooks