Initial Results of An Einstein Observatory "Shallow Survey" Near HEAO-1X-ray Source Locations Schwartz, D. A. ; Remillard, R. A. ; Bradt, H. ; Brissenden, R. ; Tuohy, I. ; Buckley, D. Abstract Publication: Bulletin of the American Astronomical Society Pub Date: March 1988 Bibcode: 1988BAAS...20..735S