personal.psu.edu/users/s/l/sls576/ecba/Case%20Study%203-Schatz.pdf
http://office.microsoft.com/en-us/excel-help/if-function-HP010069829.aspx
http://php.net/manual/en/language.operators.comparison.php
http://www.w3resource.com/java-tutorial/java-conditional-operators.php
http://alvinalexander.com/java/edu/pj/pj010018
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/op2.html
http://php.net/manual/en/language.types.type-juggling.php
http://php.net/manual/en/language.types.string.php
http://msdn.microsoft.com/en-us/library/ms173105.aspx
http://www.dotnetperls.com/cast