Archer, Margaret
Routledge, 1998
Buku Teks SO
Shahid Rahman
Springer, 2012
eBooks
Stephen Ross, editor
Routledge, 2009
Buku Teks SO
Fedrizzi, Mariann
South Western Cengage Learning, 2011
Buku Teks SO
edited by Alison Pullen, Nancy Harding, Mary Phillips
Emerald, 2017
eBooks