Text and Data Mining valid from 2018-09-20
Received: 5 June 2018
Accepted: 10 September 2018
First Online: 20 September 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: For this type of study formal consent is not required. This article does not contain any studies with human participants or animals performed by any of the authors.
: Informed consent was obtained from all individual participants included in the study.