[1]
D. D. Wackerly, R. L. Scheaffer, and W. Mendenhall, Mathematical statistics with applications, 7th ed (int. student ed.). London: Thomson/Brooks/Cole, 2008.
[2]
B. Everitt, The Cambridge dictionary of statistics, 2nd ed. Cambridge: Cambridge University Press, 2002 [Online]. Available: http://eu.alma.exlibrisgroup.com/view/action/uresolver.do?operation=resolveService&package_service_id=3037228650002418&institutionId=2418&customerId=2415