Text and Data Mining valid from 2020-02-06
Received: 30 December 2019
Accepted: 1 January 2020
First Online: 6 February 2020
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: As this was a review study, no ethics approval was required.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: For this type of study, informed consent was not required.