Napier, A.S., and Stevenson, W.H. (editors), The Crawford Collection of Early Charters and Documents. Oxford, 1895.
Olafs Saga hins Helga. Edited by R. Keyser and C.R. Unger. Christiania, 1849. A saga of Saint Olaf; largely legendary.
OLRIK, AXEL, Nardisk Aandsliv i Vikingetid og tidlig Middelalder. Copenhagen, 1907. An excellent popular discussion of mediæval culture in Scandinavia.
OMAN, C.W.C., England Before the Norman Conquest. New York, 1910. (Oman, History of England in Seven Volumes, i.)
Origines Islandicæ. Edited by Gudbrand Vigfusson and F. York Powell. 2 vols. Oxford, 1905.
PALGRAVE, FRANCIS, History of Normandy and England. 4 vols. London, 1851-1864.
PARIS, MATTHEW, Chronica Majora, ed. H.R. Luard. 7 vols. London, 1872-1883. Rolls Series, No. 57.
Pertz, G.H., et al. (editors), Monumenta Germaniæ Historica, Scriptores. 30 vols. Hanover, 1826-1896.
POITIERS, WILLIAM OF, Gesta Willelmi Ducis Normannorum et Regis Angliæ, ed. André Duchesne. Paris, 1619. (Hist. Norm. Scriptores.)
POLLOCK, F., and MAITLAND, F.W., The History of the English Law Before the Time of Edward I. 2 vols. Cambridge, 1895.