Bischkopf, J. 2008. Review: Udo Kelle (2007). Die Integration qualitativer und quantitativer Methoden in der empirischen Sozialforschung [Integrating Qualitative and Quantitative Methods in Empirical Social Research: Theoretical Foundations and Methodological Concepts]. Forum Qualitative Sozialforschung / Forum: Qualitative Social Research. 9, 3 (Jul. 2008). DOI:https://doi.org/10.17169/fqs-9.3.446.