by Nancy McCormark and Catherine Cotter
Chando, 2013
eBooks
Gatrell, Caroline, author
McGraw-Hill, 2006
Buku Teks
Baird, Lloyd S., author
Business One Irwin, 1992
Buku Referensi
Drucker, Peter F. (Peter Ferdinand), 1909-2005, author
Pan Books, 1970
Buku Teks
Foster, Douglas
Longman , 1972
Buku Teks