Directionality of Solar Flare Hard X-Rays - VENERA:13 Observations Bogovalov, S. V. ; Kotov, Y. D. ; Zenchenko, V. M. ; Vedrenne, G. ; Niel, M. ; Barat, C. ; Chambon, G. ; Talon, R. Abstract Publication: Soviet Astronomy Letters Pub Date: October 1985 Bibcode: 1985SvAL...11..322B