1. Burbidge, G. R., Paris Symp. Radio Astronomy, 1958, edit. by Bracewell, R. N. (Stanford Univ. Press, 1959).
2. Ginsburg, V. L., Paris Symp. Radio Astronomy, 1958, edit. by Bracewell, R. N. (Stanford Univ. Press, 1959).
3. Burbidge, G. R., and Hoyle, F., Nuovo Cimento, 4, 558 (1956).
4. Burbidge, G. R., Burbidge, E. M., and Sandage, A. R., Rev. Mod. Phys., 35, 947 (1963).
5. Hoyle, F., and Fowler, W. A., Nature, 197, 533 (1963).