^Ingelbart, Louis Edward, Press Freedoms. A Descriptive Calendar of Concepts, Interpretations, Events, and Courts Actions, from 4000 B.C. to the Present, p40, Greenwood Publishing 1987, ISBN 0-313-25636-5, [1]
^Google Books, Ingelbart, Louis Edward, Press Freedoms. A Descriptive Calendar of Concepts, Interpretations, Events, and Courts Actions, from 4000 B.C. to the Present, Greenwood Publishing 1987, ISBN 0-313-25636-5]
Eisenstein, Elisabeth L. - Rewolucja Gutenberga, translated by: Henryk Hollender, Prószyński i S-ka publishing, Warsaw 2004, ISBN 83-7180-774-0
Ingelbart, Louis Edward - Press Freedoms. A Descriptive Calendar of Concepts, Interpretations, Events, and Courts Actions, from 4000 B.C. to the Present, Greenwood Publishing 1987, ISBN 0-313-25636-5