Robinson, Richard D.
The Dryden Press, 1978
Buku Teks
Hill, Charles W. L., author
Salemba Empat, 2014
Buku Teks
Stocking, George W., author
The Twentieth Century Fund, 1948
Buku Teks
Australian Cooperative Education, 1996
Buku Referensi
Daniels, John D.
PWS-Kent Publishing, 1993
Buku Teks