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
Nationaal Archief 60 Alternative names for repository: National Archives of the Netherlands The Hague, National Archives Algemeen Rijksarchief
City: The Hague
Alternative names for city: Den Haag
Country: Netherlands
National Library of Ireland - Alternative names for repository: NLI
City: Dublin
Country: Republic of Ireland
National Library of Russia - Alternative names for repository: Российская национальная библиотека Bibliothèque nationale de Russie
City: St Petersburg
Alternative names for city: Leningrad
Country: Russia
National Library of Scotland, Manuscript Collections 12 City: Edinburgh
Country: Scotland, United Kingdom
National Library of Wales, Department of Collection Services 126 Alternative names for repository: NLW
City: Aberystwyth
Country: Wales, United Kingdom
National Maritime Museum, Greenwich - City: London
Country: England
Natural History Museum 115 Alternative names for repository: NHM
City: London
Country: England, United Kingdom
Newcastle Literary and Philosophical Society 1 Alternative names for repository: The Lit & Phil
City: Newcastle upon Tyne
Country: England
New York Public Library 106 City: New York, NY
Country: United States of America
Niedersächsische and Leibniz Bibliothek 44 City: Hannover
Alternative names for city: Hanover
Country: Germany
Niedersächsisches Staatsarchiv 45 Alternative names for repository: Niedersächsisches Landesarchiv - Staatsarchiv Niedersächsisches Staatsarchiv, Aurich
City: Aurich
Country: Germany
Northamptonshire Record Office 8 City: Northampton
Country: England, United Kingdom
Nottingham University Library 3 City: Nottingham
Country: England
Národní knihovna 25 Alternative names for repository: Klementinum
City: Praha
Alternative names for city: Prague
Country: Czech Republic