Ridley, Mark
Blackwell Scientific, , 1993"
Buku Teks
Ridley, Nicholas
Fontana, 1992
Buku Teks SO
Executing Agency of Rehabilitation and Reconstruction for Aceh and Nias, 2009
Multimedia
edited by Douglas Street
Olympic Marketing, 1984
Buku Teks SO
edited by Steven J. Ross
West Sussex Wiley Blackwell, 2014
Buku Teks SO