Georgia Performance Standards (2012) Retrieved 12/1/2012 https://www.georgiastandards.org/Pages/default.aspx

Kutasoftware (2012)  Retrived 12/20/2012 from http://kutasoftware.com/

Mathslice (2012) Retrieved 12/15/2012 from http://www.mathslice.com/ratios_ws.php

Stapel, E (2013) Purplemath.com Retrieved 12/12/2012 from http://www.purplemath.com/modules/ratio.htm