Stewart, F. H. (tháng 9 năm 1942). “Chemical data on a silica-poor argillaceous hornfels and its constituent minerals”. Mineralogical Magazine and Journal of the Mineralogical Society. 26 (178): 260–266. Bibcode:1942MinM...26..260S. doi:10.1180/minmag.1942.026.178.04.
durham.gov.uk
Lawrence D. J. D., Vye C. L., Young B. et al., 2004. Durham Geodiversity Audit. Durham: Durham County Council, tr. 20
Stewart, F. H. (tháng 9 năm 1942). “Chemical data on a silica-poor argillaceous hornfels and its constituent minerals”. Mineralogical Magazine and Journal of the Mineralogical Society. 26 (178): 260–266. Bibcode:1942MinM...26..260S. doi:10.1180/minmag.1942.026.178.04.