Nasjonalbiblioteket – The National Library of Norway
This library is located in Oslo.
The web-site is both in Norwegian and English.
Otherwise the main libraries of interest will be those of the various universities.
The Diplomatarium Norvegicum
Language: Norwegian and English.
This database contains the printed edition of the Diplomatarium Norvegicum. The edition consists of 22 volumes containing the transcription of approximately 20 000 diplomas connected to Norway in the period 1050 to 1590.