Text and Data Mining valid from 2019-09-19
Received: 21 March 2019
Accepted: 8 July 2019
First Online: 19 September 2019
Compliance with ethical standards
: All authors declare that they have no conflict of interest.
: The procedures followed were in accordance with the ethical standards of the institutional and/or research committee and with the 1964 Helsinki Declaration and its later amendments.