Collisional Excitation of Forbidden Lines Billings, A. ; Czyzak, S. J. ; Krueger, T. K. ; Saraph, H. E. ; Seaton, M. J. ; Shemming, J. Abstract Publication: Physics of Electronic and Atomic Collisions: ICPEAC IV Pub Date: 1965 Bibcode: 1965peac.conf..201B