@misc{indiciae48037e7af3cd,
  title = {Upper limits from hard X-ray observations of five BL Lacertae objects},
  author = {Bezler, M. and Gruber, D. E. and Rothschild, R. E.},
  year = {1988},
  url = {https://ntrs.nasa.gov/citations/19890029313},
  note = {Source identifier: 19890029313}
}