Johann Peter Gumbert, Sizes and Formats, Ancient and Medieval Book Materials and Techniques (Erice 18-25 sett. 1992), Studi e testi, 357-358, Città del Vaticano, Biblioteca Apostolica Vaticana, 1993
Johann Peter Gumbert, Sizes and Formats, Ancient and Medieval Book Materials and Techniques (Erice 18-25 sett. 1992), Studi e testi, 357-358, Città del Vaticano, Biblioteca Apostolica Vaticana, 1993