BL.ukArchived 12 March 2011 at the Wayback Machine, consulted in 2007. The figures are subject to slight change as new copies are reported. Exact figures are given but should be treated as close estimates; they refer to extant editions.
"ISTC". Archived from the original on 18 November 2021. Retrieved 16 May 2009.
J. Green, F. McIntyre, P. Needham (2011), "The Shape of Incunable Survival and Statistical Estimation of Lost Editions", Papers of the Bibliographical Society of America 105 (2), pp. 141–175. doi:https://doi.org/10.1086/680773
Glomski, J. (2001). "Incunabula Typographiae: seventeenth-century views on early printing". The Library. 2 (4): 336. doi:10.1093/library/2.4.336.
Carter, John; Barker, Nicolas (2004). ABC for Book Collectors (8th ed.). New Castle, Del.: Oak Knoll Press and the British Library. p. 172. ISBN1-58456-112-2. Archived from the original(PDF) on 21 November 2017. Retrieved 28 May 2010.
"Inkunabeln & Blockbücher" (in German). Universitäts- und Landesbibliothek Tirol. Archived from the original on 25 September 2020. Retrieved 3 September 2020.
Carter, John; Barker, Nicolas (2004). ABC for Book Collectors (8th ed.). New Castle, Del.: Oak Knoll Press and the British Library. p. 172. ISBN1-58456-112-2. Archived from the original(PDF) on 21 November 2017. Retrieved 28 May 2010.
BL.ukArchived 12 March 2011 at the Wayback Machine, consulted in 2007. The figures are subject to slight change as new copies are reported. Exact figures are given but should be treated as close estimates; they refer to extant editions.
"ISTC". Archived from the original on 18 November 2021. Retrieved 16 May 2009.
"Inkunabeln & Blockbücher" (in German). Universitäts- und Landesbibliothek Tirol. Archived from the original on 25 September 2020. Retrieved 3 September 2020.
"Inkunabeln" (in German). Universitätsbibliothek Erlangen-Nürnberg. Archived from the original on 29 September 2020. Retrieved 3 September 2020.
Whitesell, David (2006). First supplement to James E. Walsh's Catalogue of the fifteenth-century printed books in the Harvard University Library. Cambridge, Mass.: Houghton Library. p. xiii. ISBN978-0-674-02145-7. OCLC71691077.