Michael S. Lewis-Beck, editor
Sage Publications, 1993
Buku Referensi
Kuzma, Jan W., author
McGraw-Hill, 2000
Buku Teks
Riffenburgh, Robert H., author
lsevier Science, 2012
Buku Teks
Lancaster, H.O., author
John Wiley & Sons, 1974
Buku Teks
Hill, Austin Bradford, author
The Lancet Limited, 1971
Buku Teks