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Bestelakorik adierazi ezean, itemaren baimena horrela deskribatzen da:This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Attribution 4.0 International (CC BY 4.0) CC0 1.0 Universal (CC0 1.0) Public Domain Dedication