Bl-Lacertae Objects as X-Ray Sources - the EXOSAT Observations Maccagni, D. ; Garilli, B. ; Barr, P. ; Giommi, P. ; Pollock, A. Abstract Publication: BL Lac Objects Pub Date: 1989 DOI: 10.1007/BFb0031173 Bibcode: 1989LNP...334..281M