Juul S & Frydenberg M 2014, An Introduction to Stata for Health Researchers, 4th edn, StataCorp LP, College Station, Texas.

Rodriguez, G 2016, Stata tutorial, Princeton University, viewed 23 February 2016, <http://data.princeton.edu/stata/default.html>

Social Science Computing Cooperative (SSCC) 2016, Stata for Researchers: Introduction, SSSC, viewed 23 February 2016, <http://www.ssc.wisc.edu/sscc/pubs/sfr-intro.htm>

StataCorp 2014, NetCourse 101: Introduction to Stata, StataCorp. Information about the course available from: http://www.stata.com/netcourse/intro-nc101/  

StataCorp 2016, Stata: data analysis and statistical software, StataCorp, viewed 23 Feruary 2016, <http://www.stata.com/>