Text and Data Mining valid from 2019-11-09
Received: 24 July 2019
Accepted: 24 October 2019
First Online: 9 November 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors. All procedures performed in this study were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: For this type of study, formal consent is not required.