Autograph of Georgios Gemistos Plethon
Original manuscript of the Byzantine scholar.
Catholic Encyclopedia: Plethon, Georgius Gemistus
An encyclopedia entry with a short list of secondary literature by William Turner.
George Gemistos Plethon on God: Heterodoxy in Defe
An essay by Darien C. DeBolt. From the Paideia Project.
Wikipedia: George Gemistos Plethon
An encyclopedia entry. Incorporates text from the public domain 1911 Encyclopædia Britannica.