Text and Data Mining valid from 2020-01-22
Received: 13 September 2019
Accepted: 7 January 2020
First Online: 22 January 2020
Ethics approval and consent to participate
: The author declares that the manuscript including generated data is in accordance with the Declaration of Helsinki, with national ethical legal regulations and with the ethics committee of the University of Regensburg, Germany.
: Not applicable.
: The author declares that there are no competing interests.