Rerum Britannicarum medii aevi scriptores;
or Chronicles and memorials of Great Britain and Ireland during the Middle Ages.

APA Citation

Great Britain. Public Record Office. (18581965). Rerum Britannicarum medii aevi scriptores: or Chronicles and memorials of Great Britain and Ireland during the Middle Ages. London: Longman [etc.].

MLA Citation

Great Britain. Public Record Office. Rerum Britannicarum Medii Aevi Scriptores: Or Chronicles And Memorials of Great Britain And Ireland During the Middle Ages. London: Longman [etc.], 18581965.

Warning: These citations may not always be complete (especially for serials).