Text and Data Mining valid from 2018-02-28
Received: 27 August 2017
Accepted: 22 February 2018
First Online: 28 February 2018
Compliance with ethical standards
: We declare no conflict of interest.
: All procedures performed were 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.