In Abbott, M. L. and McKinney, J. (eds): Understanding and Applying Research Design, Wiley
Link: http://www.websm.org/index.php?fl=2&lact=1&bid=15727&parent=12
Data has been last edited on Feb 21 2013
Link: http://www.websm.org/index.php?fl=2&lact=1&bid=15727&parent=12
Data has been last edited on Feb 21 2013