1. Bacher, J., Pöge, A., & Wenzig, K. (2010). Clusteranalyse. Anwendungsorientierte Einführung in Klassifikationsverfahren (3rd extended, completely revised and redesigned ed.). Munich: Oldenbourg. Accessed December 12, 2019, from http://www.oldenbourg-link.com/isbn/9783486710236.
2. Backhaus, K., Erichson, B., Plinke, W., & Weiber, R. (2016). Multivariate Analysemethoden. Eine anwendungsorientierte Einführung (14th, revised and updated ed.). Berlin: Springer Gabler.
3. Bensiek, T. (2013). Systematik zur reifegradbasierten Leistungsbewertung und -steigerung von Geschäftsprozessen im Mittelstand (Vol. 357). Dissertation, Faculty of Mechanical Engineering, University of Paderborn. HNI-Verlagsschriftenreihe.
4. Blessing, L. T. M., & Chakrabarti, A. (2009). DRM, a Design Research Methodology. London: Springer. Accessed December 12, 2019, from http://site.ebrary.com/lib/alltitles/docDetail.action?docID=10310350.
5. Bley, K., Leyh, C., & Schäffer, T. (2016). Digitization of German Enterprises in the Production Sector. Do they know how “digitized” they are? In Surfing the IT innovation wave. 22nd Americas Conference on Information Systems (AMCIS 2016): San Diego, CA, 11–14 August 2016. Americas Conference on Information Systems; Association for Information Systems; AMCIS (pp. 736–746). Red Hook, NY: Curran Associates Inc.