edited by Clifton R. Wharton
Aldine Publishig, 1969
Buku Teks
edited by Carl Eicher and Lawrence Witt
McGraw-Hill , 1964
Buku Teks
World Bank
Oxford University Press, 1982
Buku Teks
Sachs, Ignacy
Polish Scientific Publishers , 1964
Buku Teks
Schultz, Theodore W., author
McGraw-Hill, 1953
Buku Teks