Text and Data Mining valid from 2017-02-20
Received: 28 January 2017
Accepted: 30 January 2017
First Online: 20 February 2017
Compliance with ethical standards
: On behalf of all authors, the corresponding author states that there is 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.