@book{ 0-138862804X, title = {Triangulation and primary traverse, 1916 - 1918}, series = {U.S. Geol. Survey Bulletin}, author = {Birdseye, C. H.}, address = {Washington, D.C.}, publisher = {U.S. G.P.O.}, year = {1923}, language = {English}, note = {Includes index}, url = {https://katalog.ub.tu-freiberg.de/Record/0-138862804X} }