Kopera, J. P., P. House, K., Schmidt, M. & Clark, R. Guiding principles for use of digital technology in geologic data collection and distribution. Abstracts with Programs - Geological Society of America 46, 75 - 75 (2014).

MassGIS. at <http://www.mass.gov/anf/research-and-tech/it-serv-and-support/application-serv/office-of-geographic-information-massgis/>

PostGIS. at <http://postgis.refractions.net/>