Institute for Scientific co-coperation, [date of publication not identified]
Majalah, Jurnal, Buletin
Blumner, Sidney M.
Kendall Hunt, 1971
Buku Teks
Reitaku International Journal of Economic Studies,
Majalah, Jurnal, Buletin
Reder, Melvin Waren
Columbia University Press , 1947
Buku Teks
Polak, Fred. L.
H. E. Stenfert Kroese's, 1951
Buku Teks