@misc{indiciae4ded402e348c,
  title = {X-ray observations of BL Lacertae objects},
  author = {Mushotzky, R. F. and Boldt, E. A. and Holt, S. S. and Serlemitsos, P. J. and Swank, J. H. and Rothschild, R. H. and Pravdo, S. H.},
  year = {1978},
  url = {https://ntrs.nasa.gov/citations/19790032882},
  note = {Source identifier: 19790032882}
}