@article{200520,
      recid = {200520},
      author = {Pollastro, Richard M.},
      title = {Acid-insoluble residue/carbonate content of the Upper  Cretaceous Niobrara Formation, Berthoud field, Denver  basin, Colorado a key factor for understanding natural  fracturing in chalks? / [microform] :},
      publisher = {Dept. of the Interior, U.S. Geological Survey :},
      address = {[Denver CO] :},
      pages = {1 v.},
      year = {1991},
      note = {Distributed to depository libraries in microfiche.},
      url = {http://library.usi.edu/record/200520},
}