Research Report
Foutse Khomh, Yann-Gaël Guéhéneuc, and Guiliano Antoniol. Playing Roles in Design Patterns: An Empirical Descriptive and Analytic Study. Technical report EPM-RT-2009-03, École Polytechnique de Montréal, April 2009.
The link address is: http://www-etud.iro.umontreal.ca/~ptidej/yann-gael/Work/Publications/Documents/Research+report+Design+Patterns+Roles+April09.doc.pdf