About the Authors

Helena Mihaljević-Brandt

Contributed equally to this work with: Helena Mihaljević-Brandt, Lucía Santamaría, Marco Tullney

helena.m-b@t-online.de (HMB); lucia.santamaria@ymail.com (LS); marco.tullney@tib.eu (MT)

Affiliation Independent Researcher, Berlin, Germany

Lucía Santamaría

Contributed equally to this work with: Helena Mihaljević-Brandt, Lucía Santamaría, Marco Tullney

helena.m-b@t-online.de (HMB); lucia.santamaria@ymail.com (LS); marco.tullney@tib.eu (MT)

Affiliation Independent Researcher, Potsdam, Germany

Marco Tullney

Contributed equally to this work with: Helena Mihaljević-Brandt, Lucía Santamaría, Marco Tullney

helena.m-b@t-online.de (HMB); lucia.santamaria@ymail.com (LS); marco.tullney@tib.eu (MT)

Affiliation German National Library of Science and Technology (TIB), Hannover, Germany

Competing Interests

We have the following interests: HMB was affiliated to The unbelievable Machine Company GmbH during the course of the study. LS was affiliated to komoot GmbH during the course of the study. HMB and LS were formerly involved with FIZ Karlsruhe as field editors of the zbMATH service; HMB was also the deputy head of department of mathematics and computer science at FIZ Karlsruhe. There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceptualization: HMB LS MT. Data curation: HMB LS MT. Formal analysis: HMB LS MT. Funding acquisition: HMB LS MT. Investigation: HMB LS MT. Methodology: HMB LS MT. Project administration: HMB LS MT. Resources: HMB LS MT. Software: HMB LS MT. Supervision: HMB LS MT. Validation: HMB LS MT. Visualization: HMB LS MT. Writing – original draft: HMB LS MT. Writing – review & editing: HMB LS MT.