* [https://web.archive.org/web/20190429134318/http://www.pennamagazine.com/en/vintage_pens/the-short-life-of-the-colorado-_29] Articolo sul sito dismesso di ''"Penna Magazine"'' | * [https://web.archive.org/web/20190429134318/http://www.pennamagazine.com/en/vintage_pens/the-short-life-of-the-colorado-_29] Articolo sul sito dismesso di ''"Penna Magazine"'' |