American Society of Landscape Architects – www.asla.org

American Public Gardens Association – www.publicgardens.org/content/historic-landscapes

Alliance for Historic Landscape Preservation – www.ahlp.org/

Cultural Landscape Foundation – http://tclf.org/

Dumbarton Oaks Research Library and Collection – www.doaks.org/

Southern Garden History Association – www.southerngardenhistory.org/

National Association for Olmsted Parks – www.olmsted.org

International Council on Monuments and Sites (ICOMOS)

Dry Stone Conservancy

The Garden Conservancy

Association for Preservation Technology International

American Society of Landscape Architects

National Trust for Historic Preservation

National Conference of State Historic Preservation Officers

International Society of Arboriculture

Landscape Institute

Wave Hill, CATALOG of landscape records

Preserving Historic Roads

Student Conservation Association