3. Bailey P, Derbyshire J, Harding A, Middleton A, Rayson K, Syson L. Assessing the impact of a study skills program on the academic development of nursing diploma students at Northumbria University, UK. Health Info Libr J. 2007; 24(Suppl 1):77–85.
http://dx.doi.org/10.1111/j.1471-1842.2007.00741.x.
4. Yamane T. Statistics, an introductory analysis. 2nd ed. New York (NY): Harper and Row;1967. p. 919.