Funding for this research was provided by:
Ministero dell’Istruzione, dell’Università e della Ricerca (L.232/2016.)
Text and Data Mining valid from 2019-05-27
Received: 19 January 2019
Accepted: 25 April 2019
First Online: 27 May 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.