@misc{indiciaed0a8ec1200b5,
  title = {Variable soft X-ray excesses in active galactic nuclei from nonthermal electron-positron pair cascades},
  author = {Zdziarski, Andrzej A. and Coppi, Paolo S.},
  year = {1991},
  url = {https://ntrs.nasa.gov/citations/19910062386},
  note = {Source identifier: 19910062386}
}