Andrew, J. H., Stefan, H., & Elisabeth, B. (2008). A multi-objective model for environmental investment decision making. Comput. Oper. Res., 35(1), 253–266.
Scholz, R.W. & Tietje, O. (2002). Embedded Case Study Methods. Integrating Quantitative and Qualitative Knowledge. Sage Publications. Thousand Oaks, Sage. ISBN 0761919465