Text and Data Mining valid from 2020-02-07
Received: 13 May 2019
Accepted: 30 October 2019
First Online: 7 February 2020
Ethics approval and consent to participate
: The Chair of the Research Ethics Committee of the College of Mathematics and Natural Sciences at the Heinrich-Heine-Universität Düsseldorf declared this study exempt from ethics review. All participants gave written informed consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.