Funding for this research was provided by:
Agencia Estatal de Investigación (MTM2016-75140-P)
European Observation Network for Territorial Development and Cohesion (MTM2016-75140-P)
Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia (EM2014/032)
Bulgarian National Science Fund (DN 12/4)
Received: 28 May 2019
Accepted: 17 October 2019
First Online: 25 October 2019
Ethics approval and consent to participate
: Not applicable.
: The authors declare that they do not have any competing interests in this manuscript.
: The authors confirm that the work described has not been published before (except in the form of an abstract or as part of a published lecture, review, or thesis), and that its publication has been approved by all co-authors.