@article{Pietsch2003,
  author    = {Ullrich Pietsch},
  title     = {Evidence of a density grating under light induced formation of surface relief gratings at polymers containing azobenzene moieties},
  url       = {http://scitation.aip.org/getpdf/servlet/ GetPDFServlet?filetype=pdf\&id=JAPIAU000094000002000963000001\&idtype=cvips},
  year      = {2003},
}