International Labour Office,, 1966
Buku Teks
edited by Barbara J. Fick
Edward Elgar Publishing, 2015
Buku Teks
Thomann, Lars
VS Verlag, 2011
eBooks
Jenks, C. Wilfred
Stevens & Sons Limited, 1960
Buku Teks
Hadiwardojo
P.P. AKRI Bhayangkara, 1970
Buku Klasik