1. Altman DG (1991) Practical statistics for medical research. Chapman and Hall, London
2. Anscombe FJ (1973) Graphs in Statistical Analysis. Am stat 27:17–21
3. Cox DR (2006) Principles of statistical inference. Cambridge University Press, Cambridge
4. Everitt BS (2003) The Cambridge dictionary of statistics. Cambridge University Press, Cambridge
5. Greenwood PE, Nikulin MS (1996) A guide to chi-squared testing. Wiley, New York