https://theconversation.com/guernica-una-invocacion-encapsulada-203519
http://www.ilo.org/global/publications/books/WCMS_605078/lang–en/index.htm
https://www.ips-journal.eu/index.php?id=343&L=0&tx_news_pi1%5Bnews%5D=3433&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&cHash=d423ae64c4b25e2b5dc104f032109b1e
http://www.beaconforfreedom.org/liste.html?tid=415&art_id=475%20