* [https://web.archive.org/web/20160527142137/http://www.rickconner.net:80/penspotters/omas.html] Articolo con qualche informazione storica | * [https://web.archive.org/web/20160527142137/http://www.rickconner.net:80/penspotters/omas.html] Articolo con qualche informazione storica |