Fuentes consultadas1. WWW VIAF, 08/05/2018 http://viaf.org/viaf/148880500
2. WWW Wikipedia, 08/05/2018: Psion was a designer and manufacturer of mobile handheld computers for commercial and industrial applications. The company was headquartered in London, England with major operations in Mississauga, Ontario, Canada https://en.wikipedia.org/wiki/Psion_(company)