Text and Data Mining valid from 2019-01-01
Received: 12 December 2018
Accepted: 18 December 2018
First Online: 6 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: For this type of study, formal consent is not required.