Barlowe, Raleigh, author
Prentice-Hall, 1958
Buku Teks
Truett, Lila J.
South-Western, 1984
Buku Teks
Nachrowi Djalal Nachrowi, author
2009
Artikel Jurnal
Nagoya University of Commerce and Business,
Majalah, Jurnal, Buletin
Douglas, Mary, author
Basic Books, 1979
Buku Teks