@article{Petrie_Mitchell_1867, title={Notice of some Rude Stone Implements found in Orkney}, volume={7}, url={http://journals.socantscot.org/index.php/psas/article/view/5319}, DOI={10.9750/PSAS.007.135.136}, journal={Proceedings of the Society of Antiquaries of Scotland}, author={Petrie, George and Mitchell, Arthur}, year={1867}, month={Nov.}, pages={135-136} }