Funding for this research was provided by:
Text and Data Mining valid from 2019-10-28
Received: 14 April 2019
Accepted: 11 September 2019
First Online: 28 October 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interests.
: This article does not contain any studies with human participants performed by any of the authors.
: Not applicable.