@article{226745,
      recid = {226745},
      author = {Tweto, Ogden,},
      title = {Rock units of the Precambrian basement in Colorado /},
      publisher = {U.S. G.P.O.,},
      address = {Washington :},
      pages = {iii, 54 p. :},
      year = {1987},
      note = {Fold. col. map in pocket.},
      url = {http://library.usi.edu/record/226745},
}