Definition of dolmen:
portal tomb, cromlech.
- "A further contribution to the study of the mortuary customs of the North American Indians First Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1879-80, Government Printing Office, Washington, 1881, pages 87-204", H. C. Yarrow.
- "A Manual of the Antiquity of Man", J. P. MacLean.
- "Rough Stone Monuments and Their Builders", T. Eric Peet.