Mitchell, Michael N., author
Stata Press, 2012
Buku Teks
Ketchum, Paul A., author
John Wiley & Sons, 1984
Buku Teks
editors, Stephen J. Williams, Paul R. Torrens
Delmar , 1998
Buku Teks
McKenzie, James F., author
Jones and Bartlett, 2005
Buku Teks
Wilner, Daniel M., author
Macmillan, 1973
Buku Teks