http://leiden.dachs-archive.org/archive/citrep/vancrevel2008/20080215/www.cipherjournal.com/html/patton.html http://leiden.dachs-archive.org/archive/citrep/vancrevel2008/20080215/www.cipherjournal.com/html/patton.html http://leiden.dachs-archive.org/archive/citrep/vancrevel2008/20080215/www.cipherjournal.com/html/patton.html