* [http://web.archive.org/web/20060514223746/http://www.tryphon.it/pens/history.htm] An article in the [[Settimo Torinese]] district, with references to Williamson with dated information that traces her back to the American namesake
* [http://web.archive.org/web/20130308045910/http://www.pentrace.net/2002/article032802_170.html] An article on the brand essentially identical to the previous one
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* http://www.tryphon.it/pens/history.htm
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* [http://xoomer.virgilio.it/leiacopi/williamson_fset.htm] A page from Letizia Jacopini's old website, dated information about the firm, unfortunately the 1905/6 AD is not visible