
http://www.europarl.europa.eu/sides/getDoc.do?pubRef=-%2F%2FEP%2F%2FNONSGML%2BCOMPARL%2BPE-602.995%2B01%2BDOC%2BPDF%2BV0%2F%2FEN

https://www.ipg-journal.de/interviews/artikel/die-gruene-falle-3380/

http://upceo.ceo.gencat.cat/wsceop/6508/Resumen%20en%20espa%C3%B1ol%20-874.pdf