Derry, Gregory N.
Princeton University Press , 1999
Buku Teks SO
Foster, Lynn E
Prentice-Hall, 2006
Buku Teks SO
University of technology,
Majalah, Jurnal, Buletin
editors, Linda A. Macaulay, Ian Miles, Jennifer Wilby, Yin Leng Tan, Liping Zhao, Babis Theodoulidis
Springer, 2012
eBooks
Sawyer, R. Keith
Oxford University Press, 2006
Buku Teks SO