Napitupulu, Darmawan, author
Kementerian Dalam Negeri RI, 2017
Artikel Jurnal
elsevier, 2016
Buku Teks
Sobel, Michael I., author
University of Chicago, 1987
Buku Teks
Bauchet, Pierre
Fredrick A. Praeger Published , 1964
Buku Teks
Wittwer, Glyn, editor
Springer, 2012
eBooks