Text and Data Mining valid from 2020-02-15
Received: 21 July 2019
Accepted: 9 January 2020
First Online: 15 February 2020
Compliance with ethical standards
: The authors have no conflicts of interest to declare.
: For this type of study ethical approval is not required.
: This article does not contain any studies with human participants performed by any of the authors.
: For this type of study formal consent is not required.