http://coa.inducks.org/story.php?c=W+WDC+104-02

Carl Barks 1949 L'eredità di Paperino (The Sunken Yacht)

http://goodcomics.comicbookresources.com/2006/10/19/comic-book-urban-legends-revealed-73/

http://www.iusmentis.com/patents/priorart/donaldduck/

http://www.starch.dk/isi/kroyer/schrooge.asp **