Note: every manifestation of a letter is counted, so the number of documents in a repository may be larger than the number of letters.

Repository Number of documents Further details
Fitzwilliam Museum (Department of Manuscripts and Printed books) 1 City: Cambridge
Country: England, United Kingdom
Folger Shakespeare Library 109 City: Washington, DC
Country: United States of America
Fondation Custodia, Frits Lugt Collection 8 Alternative names for repository: Institut Néerlandais Institut Neerlandais
City: Paris
Country: France
Forschungsbibliothek Gotha der Universität Erfurt 31 Alternative names for repository: Landesbibliothek Gotha Universitäts- und Forschungsbibliothek Erfurt/Gotha [until 19 March 2018] Universitätsbibliothek Erfurt
City: Gotha
Country: Germany