OBSERVATIONS OF THE LIMB SOLAR-FLARE ON 1980 APRIL 30 WITH THE SMM X-RAY POLYCHROMATOR by Gabriel, A, Acton, L, Culhane, J, Phillips, K, Wolfson, C, Rapley, C, Antonucci, E, Bentley, R, Jordan, C, Kayat, M, Leibacher, J, Levay, M, Sherman, J, Strong, K, Veck, N