Text and Data Mining valid from 2018-04-17
Received: 25 January 2018
Accepted: 10 April 2018
First Online: 17 April 2018
Compliance with ethical standards
: Author PL declares no conflicts of interest. Author EF declares no conflicts of interest.
: All procedures performed in studies involving human participants 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.
: No consent was needed as this is a review paper.