Text and Data Mining valid from 2019-05-07
Received: 21 December 2018
Accepted: 25 April 2019
First Online: 7 May 2019
Compliance with ethical standards
: All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions.
: The authors declare that they have no conflict of interest.