Interhemispheric observations of impulsive nitrate enhancements associated with the four large ground-level solar cosmic ray events (1940–1950), L. Kepko, Harlan E. Spence, D. F. Smart, M. A. Shea
Physics & Astronomy

Solar proton events for 450 years: The Carrington event in perspective, M. A. Shea, D. F. Smart, K. G. McCracken, G. A. M. Dreschhoff, Harlan E. Spence
Physics & Astronomy

Two groups of extremely large> 30MeV solar proton fluence events, D. F. Smart, M. A. Shea, Harlan E. Spence, L. Kepko
Physics & Astronomy