TY  - RPRT
TI  - Aeromagnetic map of the Ashburnham quadrangle, Worcester and Middlesex Counties, Massachusetts, and Cheshire and Hillsborough Counties, New Hampshire
AU  - Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey
PY  - 1971
DO  - 10.3133/gp729
UR  - https://pubs.usgs.gov/publication/gp729
ID  - gp729
ER  -