Text and Data Mining valid from 2018-11-30
Received: 24 September 2018
Accepted: 17 November 2018
First Online: 30 November 2018
Compliance with ethical standards
: This work met compliance with ethical standards.
: No conflict of interest to report.
: 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.