@article{25356,
      author       = "Hristov, Vladimir and Symposium Sofia, 1969",
      title        = "Proposal by the Bulgarian National Committee on Geodesy and
                      Geophysics for a Specification of the Geodetic Reference
                      System 1967  ",
      year         = "1969",
      note         = "1 seš., Bulgarien Academy of Sciences National Committee
                      on Geodesy and Geophysics., International Symposim on
                      Continental Networks Sofia, 1969",
}