Ostfriesisches Urkundenbuch
By: Hrsg. von Ernst Friendlaender
Publisher: Martin Sändig
Published: 1968
Place of publication: Wiesbaden
Language: ger
Subjects: History; Sources; Low German language; Dialects
Notes: "Unveränderter Neudruck der Ausgabe von 1878-81."

The documents from 1420 on are with a few exceptions in the Low German dialect of East Friesland.