Kopera, J. P. Preliminary bedrock geologic map of the Ayer quadrangle, Massachusetts. Open-File Report (2006). at <http://www.geo.umass.edu/stategeologist/>

Kopera, J. P., Mabee, S. B. & Powers, D. C. Preliminary fracture characterization map of the Ayer quadrangle, Massachusetts. Open-File Report (2006).