CalTopo - Backcountry topographic maps. at <http://caltopo.com/>

Historical Cadastral Maps and Illustrations. at <http://www.historicmapworks.com/>

Scanned "newer" 1:25K topographic maps (from MassGIS). at <http://www.mass.gov/anf/research-and-tech/it-serv-and-support/application-serv/office-of-geographic- information-massgis/datalayers/imquad.html>

UNH Historic Map Library for New England. at <http://docs.unh.edu/nhtopos/nhtopos.htm>

USGS Topoview. (2014). at <http://ngmdb.usgs.gov/maps/TopoView/>