Case Study research : Robert K. Yin
The case study is but one of several ways of doing social science research.
As a research endeavor, the case study contributes uniquely to our knowl- edge of individual, organizational, social, and political phenomena. Not surprisingly, the case study has been a common research strategy in psychol- ogy, sociology, political science, business, social work, and planning. (2)
Definition of the Case Study as a Research Strategy