Jenks, C. Wilfred
Stevens & Sons Limited, 1960
Buku Teks
Haas, Ernst B.
Stanford University Press, 1970
Buku Teks
edited by Barbara J. Fick
Edward Elgar Publishing, 2015
Buku Teks
Thomann, Lars, author
VS Verlag, 2011
eBooks
Haas, Ernst B.
Standford University Press, 1970
Buku Teks