Chowns T, Dobbs C.  2006.  Valley and Ridge Geologic Province. New Georgia Encyclopedia.

Clancy K.  1996.  Natural communities of Delaware.

Comer P, Faber-Langendoen D, Evans R, Gawler S, Josse C, Kittel G, Menard S, Pyne M, Reid M, Schulz K et al..  2003.  Ecological systems of the United States: a working classification of U.S. terrestrial systems.

Conley G.  2003.  European elm bark beetle and Dutch elm disease in Seattle. Accessed 2015

Cook CW.  2008.  American beech (Fagus grandifolia) .

Cornell Lab of Ornithology.  2015.  Red-shouldered Hawk.

Corporation of Harpers Ferry.  2018.  History of Harpers Ferry.

Cowardin LM, Carter V, Golet FC, Laroe ET.  1979.  Classification of wetlands and deepwater habitats of the United States.

Coxe R.  2006.  Prime Hook National Wildlife Refuge. Vegetation inventory.

Coxe R.  2007.  Guide to Delaware vegetation communities.

Davis AF, Andersen SB, Lungren JA, Wilkinson AM, Belfonti JR, Kunsman JR, Stanosz JC.  1992.  A natural areas inventory of Delaware County, Pennsylvania.

Deinlein M.  2003.  Yellow-bellied sapsucker: the master sap tapper.

Department of the Environment.  2010.  Rock Creek watershed implementation plan (WIP).

District of Columbia Department of Health.  2004.  Final Total Maximum Daily Loads for Metals in Rock Creek.

District of Columbia Water and Sewer Authority.  2010.  Combined Sewer System.

District of Columbia Water and Sewer Authority.  2017.  Rock Creek Green Infrastructure Project A.

District of Columbia Water and Sewer Authority.  2013.  Anacostia River Tunnel Project.

District of Columbia Water and Sewer Authority.  2017.  Northeast Boundary Tunnel Project.

District of Columbia Water and Sewer Authority.  2010.  Clean Rivers Project.

Edinger GJ, Evans DJ, Gebauer S, Howard TG, Hunt DM, Olivero AM.  2002.  Ecological communities of New York state. Second edition. A revised and expanded edition of Carol Reschke's ecological communities of New York State. (Draft for review).

Ehrenfeld JG.  1977.  Vegetation of Morristown National Historical Park: ecological analysis and management alternatives. Final Report.

Elkinton JS, Healy WM, Liebhold AM, Buonaccorsi JP.  2002.  Gypsy moths and forest dynamics. Pages 100-112 in Oak Forest Ecosystems (W.J. McShea and W.M. Healy, editors).

Enser R.  1993.  Natural community classification for Rhode Island. Draft.

Environmental-Literary-Council.  2009.  Buffalo.

Eyre FH.  1980.  Forest cover types of the United States and Canada, FH Eyre, editor .