1. Jeans, J. H., Astronomy and Cosmogony, chap. IX (Cambridge Univ. Press, 1928).
2. Alfvén, H., On the Origin of the Solar System (Oxford Univ. Press, 1954).
3. Hoyle, F., Quart. J. Roy. Astro. Soc., 1, 28 (1960).
4. Urey, H., The Origin of the Planets (Oxford Univ. Press, 1952).
5. Jeffreys, H., The Earth (Cambridge Univ. Press, 1952).