2018 TheAuthors. Published by Elsevier Inc.This is an open access article under the CCBY license
(http://creativecommons.org/licenses/by/4.0/).
Attribution 4.0 International (CC BY 4.0)
Bestelakorik adierazi ezean, itemaren baimena horrela deskribatzen da:2018 TheAuthors. Published by Elsevier Inc.This is an open access article under the CCBY license (http://creativecommons.org/licenses/by/4.0/). Attribution 4.0 International (CC BY 4.0)