Konperensi II PSL, 1981
Buku Teks
Baaz, Abdul Aziz bin Abdullah bin
IAIN Sumatera Utara, [Date of publication not identified]
Buku Teks SO
Asy-Syarbashi, Ahmad
Lentera Basritama, 2001
Buku Teks SO
ECPAT in Indonesia, 2006
Buku Teks
Yayasan Bina pajak, 1979
Buku Teks SO