Petersen, Niels Matthias Hervarar Saga Ok Heiðreks Konungs Petersen, Niels Frederick Flora of Nebraska; a List of the Conifers and Flowering Plants of the State, With Keys for Their Det Petersen, Niels Matthias Danmarks Historie I Hedenold: Hedenskab Og Kristendom. 1854 Petersen, Niels Leitfaden zur Nordischen Alterthumskunde. Petersen, Niels Leitfaden zur Nordischen Alterthumskunde. Petersen, Niels Matthias Hervarar Saga Ok Heiðreks Konungs Sök bara efter: Petersen, Niels Frederick
