1928–2012 Obituary Condolences Robert (Bob) Ragen, su legacy.com. URL consultato il 1º gennaio 2016 (archiviato dall'url originale il 18 dicembre 2017).
«Bob holds over 80 patents awarded during his work as Director of RD for Friden, and Singer and as Senior Project Engineer at Xerox. He retired from Xerox RD in 1990. He is responsible for the development of the first commercial electronic calculator, the Friden 130, which has been displayed at the Smithsonian.»
