Text and Data Mining valid from 2019-03-30
Received: 2 March 2019
Accepted: 6 March 2019
First Online: 30 March 2019
Compliance with ethical standards
: The authors have no conflicts of interest.
: The study involved no research on Human participants and consent is not applicable.
: The study involved no research on animals.
: As this article does not contain any studies with human participants performed directly by any of the authors, the concept of informed consent is not applicable.