TY  - RPRT
TI  - Aeromagnetic map of the Ashby quadrangle, Middlesex and Worcester Counties, Massachusetts, and Hillsborough County, New Hampshire
AU  - Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey
PY  - 1971
DO  - 10.3133/gp730
UR  - https://pubs.usgs.gov/publication/gp730
ID  - gp730
ER  -