Barnatt, John. Stone Circles of the Peak:  A search for natural harmony.  Turnstone Books, 37 Upper Addison Gardens, London  W14 8AJ (1978)

Brown, Peter Lancaster.  Megaliths and Masterminds.  Charles Scribner's Sons, New York.  (1979)

Burl, Aubrey.  Prehistoric Stone Circles.  Shire Publications Ltd., Cromwell House, Church Street, Prinus Risborough, Aylesbury, Bucks.  Hp17 9AJ, U.K.  (1979)

Heggie, Douglas C.  Megalithic Science:  Ancient Mathematics and Astronomy in North-West Europe.  Thames and Hudson Ltd., London.  (1981)

Waerden, B.L. Van der.  Geometry and Algebra in Ancient Civilizations.  Springer-Verlag Berlin Heidelberg, Germany.  (1983)