1. Forrest, D. J. et al. 17th int. Cosmic Ray Conf., Paris 10, 5–8 (Centre d' Études Nuclèares de Saclay, 1981).
2. Chupp, E. L. et al. Astrophys. J. Lett. 244, L171–L174 (1981).
3. Chupp, E. L. The La Jolla Institute Workshop on γ-Ray Transients and Related Astrophysical Phenomena (eds Lingenfelter, R. E., Hudson, H. S. & Worrall, D. M.) 363 (AIP, New York, 1981).
4. Orwig, L. E., Frost, K. F. & Dennis, B. R. Astrophys. J. Lett. 244, L163–L166 (1981).
5. Kane, S. R. et al. Astrophys. J. (in the press).