1. The existence of refinement mappings
2. The Hawthorne effect: A reconsideration of the methodological artifact.
3. E. R. Babbie. 2010. The Basics of Social Research 5th Ed. Wadsworth Publishing. E. R. Babbie. 2010. The Basics of Social Research 5 th Ed. Wadsworth Publishing.
4. Understanding statistical power in the context of applied research;Baguley T.;Appl. Ergonom.,2006
5. V. Basili G. Caldiera and D. Rombach. 1994. Goal/question/metric paradigm. In Encyclopedia Software Engineering 1 John Wiley and Sons 528--532. V. Basili G. Caldiera and D. Rombach. 1994. Goal/question/metric paradigm. In Encyclopedia Software Engineering 1 John Wiley and Sons 528--532.