Text and Data Mining valid from 2019-03-06
Received: 4 February 2019
Accepted: 1 March 2019
First Online: 6 March 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.