@article{219692,
      note = {Cover title.},
      author = {Castle, Robert O. and Gilmore, Thomas D.},
      url = {http://library.usi.edu/record/219692},
      title = {The selective salvation of Zeiss Ni 1 levelings /},
      publisher = {U.S. Geological Survey,},
      abstract = {An analysis of the results of a representative sample of  earlier Zeiss Ni 1 levelings suggests that a number of  these earlier levelings were free of any significant  magnetic error.},
      recid = {219692},
      pages = {iii, 30 p. :},
      address = {Menlo Park, Calif. :},
      year = {1994},
}