@misc{indiciaeb61a1efca051,
  title = {The Einstein Observatory and future X-ray telescopes},
  author = {Giacconi, R. and Gorenstein, P. and Murray, S. S. and Schreier, E. and Seward, F. and Tananbaum, H. and Tucker, W. H. and Van Speybroeck, L.},
  year = {1981},
  url = {https://ntrs.nasa.gov/citations/19810065421},
  note = {Source identifier: 19810065421}
}