1. Fowler, W. A., Burbidge, E. M., Burbidge, G. R., and Hoyle, F., in The Magnetic and Related Stars (edit. by Cameron, R. C.) (Mono Book Corporation, Baltimore, 1967).
2. Jaschek, C., and Jaschek, M., in The Magnetic and Related Stars (edit. by Cameron, R. C.) (Mono Book Corporation, Baltimore, 1967).