Basurto, X and Speer, J. (2012) ‘Structuring the calibration of qualitative data as sets for Qualitative Comparative Analysis (QCA)’, Field Methods, 24 (2): 155–74.

Using a study of Guatamalan local governments, these authors describe how they used qualitative data from interviews to create fuzzy sets by incorporating qualitative data analysis software as part of the process. It is an interesting article, but the end result is only a four-value fuzzy set for each set membership. As Chapter 7 in Kent (2015) explains, this will result in fairly limited analyses using fsQCA.

Verkuilen, J. (2005) ‘Assigning membership in a fuzzy set analysis’, Sociological Methods and Research, 33 (4): 462–96.

This article discusses the three main strategies for assigning fuzzy set membership values – direct subjective assignment, indirect subjective assignment, and transformation. It is non-technical, although there are a few equations that you can ignore.