Sobti, R.C.
CRC Press, Taylor & Francis Group, 2009
Buku Teks SO
edited by Martin Fransman, Gerd Junne and Annemieke Roobeek
Blackwell, 1995
Buku Teks SO
Barnum, Susan R.
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Buku Teks SO
Shayne Cox Gad.
Wiley-Interscience , 2017
Buku Referensi
Kayser, Oliver
Wiley-VCH, 2004
Buku Teks SO