Ronan Paddison, Tom Hutton, editors
Sage, 2015
Buku Teks SO
John Wiley & Sons, 2004
Buku Teks
by Ulrich Steger [and others]
John Wiley & Sons, 2004
Buku Teks
edited by Kose John, Anil K. Makhija, Stephen P. Ferris
Emerald, 2017
eBooks
Whitman, Jim
Routledge, 2005
Buku Teks SO