Text and Data Mining valid from 2019-04-13
Received: 1 December 2018
Accepted: 21 February 2019
First Online: 13 April 2019
Compliance with ethical standards
: The authors declared no conflicts of interest relevant to this article.
: 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.