Geological Survey (U.S.), Massachusetts. Department of Public Works, & Dennen, W. H. (1991). Bedrock geologic map of the Ipswich quadrangle, Essex County, Massachusetts. The Survey.
Chicago Style (17th ed.) CitationGeological Survey (U.S.), Massachusetts. Department of Public Works, and William H. Dennen. Bedrock Geologic Map of the Ipswich Quadrangle, Essex County, Massachusetts. Reston, Va.: The Survey, 1991.
MLA (9th ed.) CitationGeological Survey (U.S.), et al. Bedrock Geologic Map of the Ipswich Quadrangle, Essex County, Massachusetts. The Survey, 1991.
Warning: These citations may not always be 100% accurate.