Royal Society of New Zealand. Art. XI.—On the Fissures and Caves at the Castle Rocks, Southland; with a Description of the Remains of the Existing and Extinct Birds Found in Them from Transactions and Proceedings of the Royal Society of New Zealand (1892). Digital image. 1892. Web. <https://en.wikipedia.org/wiki/File:Harpagornis_moorei_skull.jpg>.
