found: Regional Science Research Institute.Untaxing open space, 1976.
found: The law of agricultural land preservation in the United States, 2018(John C. Keene is professor emeritus in the Department of City and Regional Planning at the University of Pennsylvania, where he teaches courses on land use law, environmental law, and strategies for sustainable development)
found: Design.upenn.edu, viewed June 13, 2019:(John Keene, Professor Emeritus of City and Regional Planning; B.A., Yale University; J.D., Harvard University; M.C.P., University of Pennsylvania; author of: Saving American Farmland: What Works?; Guiding Growth: A Primer on Growth Management for PennsylvaniaMunicipalities; The Protection of Farmland: A Reference Guidebook for State and Local Governments; and Untaxing Open Space: AnEvaluation of the Effectiveness of Differential Assessment of Farms and Open Space, along with numerous articles and reports.)