edited by Jorg Mahlich and Werner Pascha
Springer, 2012
eBooks
Sage Publications , 2018
Majalah, Jurnal, Buletin
University of technology,
Majalah, Jurnal, Buletin
by L. C. Dunn [and others]
The Unesco Press, 1956
Buku Teks SO
J. Anthony Bristow, editor
John Wiley & Sons, 1997
Buku Referensi