1. Adler, P.A., Adler, P.: Observational Techniques. In: Denzin, N.K., Lincoln, Y. (eds.) Handbook of Qualitative Research, pp. 377–393. Sage, Thousand Oaks (1994)
2. Bosch, J., Bosch-Sijtsema, P.M.: Introducing Agile Customer-Centered Development in a Legacy Software Product Line. Accepted for Software Practice and Experience (February 2011)
3. Corbin, J., Strauss, A.: Basics of qualitative research, 3rd edn. Sage, Thousand Oaks (2008)
4. Davenport, T.H.: How to Design Smart Business Experiments. Harvard Business Review (February 2009)
5. Kohavi, R., Crook, T., Longbotham, R.: Online Experimentation at Microsoft. In: Third Workshop on Data Mining Case Studies and Practice Prize (2009)