@article{54479,
      recid = {54479},
      author = {Hirsch, S. Carl.},
      title = {Guardians of tomorrow; pioneers in ecology},
      publisher = {Viking Press},
      address = {New York,},
      pages = {192 p.},
      year = {1971},
      abstract = {Brief biographies of eight American pioneers in  conservation and ecology: Henry David Thoreau, George  Perkins Marsh, Frederick Law Olmsted, John Muir, Gifford  Pinchot, George Norris, Aldo Leopold, and Rachel Carson.},
      url = {http://library.usi.edu/record/54479},
}