North American International Regional Conference Williamsburg, Va. and Philadelphia, Pa., International Centre for the Study of the Preservation and the Restoration of Cultural Property, United States. Advisory Council on Historic Preservation. International Centre Committee, & Timmons, S. (1976). Preservation and conservation: Principles and practices : proceedings of the North American International Regional Conference, Williamsburg, Virginia, and Philadelphia, Pennsylvania, September 10-16, 1972 : conducted under the auspices of the International Centre for Conservation, Rome, Italy and the International Centre Committee of the Advisory Council on Historic Preservation. Preservation Press, National Trust for Historic Preservation in the United States.

North American International Regional Conference Williamsburg, Va. and Philadelphia, Pa., International Centre for the Study of the Preservation and the Restoration of Cultural Property, United States. Advisory Council on Historic Preservation. International Centre Committee, a Sharon Timmons. Preservation and Conservation: Principles and Practices : Proceedings of the North American International Regional Conference, Williamsburg, Virginia, and Philadelphia, Pennsylvania, September 10-16, 1972 : Conducted Under the Auspices of the International Centre for Conservation, Rome, Italy and the International Centre Committee of the Advisory Council on Historic Preservation. Washington: Preservation Press, National Trust for Historic Preservation in the United States, 1976.

North American International Regional Conference Williamsburg, Va. and Philadelphia, Pa., et al. Preservation and Conservation: Principles and Practices : Proceedings of the North American International Regional Conference, Williamsburg, Virginia, and Philadelphia, Pennsylvania, September 10-16, 1972 : Conducted Under the Auspices of the International Centre for Conservation, Rome, Italy and the International Centre Committee of the Advisory Council on Historic Preservation. Preservation Press, National Trust for Historic Preservation in the United States, 1976.