Text and Data Mining valid from 2018-06-13
Received: 20 April 2018
Accepted: 6 May 2018
First Online: 13 June 2018
Compliance with ethical standards
: The authors declare that they have no competing interests.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: Informed consent is not required.
: There is no specific funding for this work.