U.S. Coast and Geodetic Survey, Jones, Ernest Lester, 1876-1929 · Washington : Govt. Print. Off. · leaf 53
Fig. 13.—ALLTRIANGULATION STATIONS ARE PERMANENTLY MARKED WITH BLOCKSOF CONCRETE INTO WHICH IS SET A BRONZE TABLET OF THE TYPE SHOWNHERE. … Special Publication No. 38.
Charts, diagrams, etc
Internet Archive · University of Toronto, Robarts Library · Public Domain Mark 1.0. Free to use for anything.
