As I have discussed in previous work (Heßbrüggen-Walter 2022), the application of digital methods to the analysis of bibliographical metadata must include reflections on the quality of the data we analyse.<ref xmlns="http://www.tei-c.org/ns/1.0" n="1" target="ftn1" /> It can be conceded that in its general form the insight is not really revolutionary: NFDI4Memory, the German research data infrastructure for historical data, has created a whole task area dedicated to questions of data quality (Mainz, Johannes Gutenberg University. n.d.). Still, it might be helpful to contribute to this ongoing discourse using concrete examples of how problems of data quality influence DH analyses in order to contribute to the creation and evaluation of “domain-relevant community standards” (Axton et al. 2016). In the present case this concerns the assessment of the quality of bibliographical metadata, in particular when used as research data in the digital humanities.