John Wiley and Sons, Inc., 1967
Buku Teks
Hoel, Paul Gerhard, 1905-, author
Wiley, 1982
Buku Teks
Hoel, Paul Gerhard, 1905-, author
Wiley, 1971
Buku Teks
Smith, Frank C., author
Richard D. Irwin, 1960
Buku Teks
Michael S. Lewis-Beck, editor
Sage Publications, 1993
Buku Referensi