International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks, 2d, Ottawa, Canadian Institute of Surveying, Canada. Surveys and Mapping Branch, & International Association of Geodesy. (1980). Second International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks: Proceedings = Deuxieme symposium international sur les problemes relies a la redefinition des reseaux geodesiques verticaux nord-americains: comptes rendus. Canadian Institute of Surveying.

International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks, 2d, Ottawa, Canadian Institute of Surveying, Canada. Surveys and Mapping Branch, and International Association of Geodesy. Second International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks: Proceedings = Deuxieme Symposium International Sur Les Problemes Relies a La Redefinition Des Reseaux Geodesiques Verticaux Nord-americains: Comptes Rendus. Ottawa: Canadian Institute of Surveying, 1980.

International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks, 2d, Ottawa, et al. Second International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks: Proceedings = Deuxieme Symposium International Sur Les Problemes Relies a La Redefinition Des Reseaux Geodesiques Verticaux Nord-americains: Comptes Rendus. Canadian Institute of Surveying, 1980.