1. Smith, W. Campbell, Adv. Sci., 7, 143 (1950); Nature, 166, 378 (1950). Urey, H. C., Geochim. Acta, 4, 72 (1953). Roy, S. K., Fieldiana, Geol., Chicago, 10, 383 (1957).
2. Sorby, H. C., Nature, 15, 495 (1877); Proc. Roy. Soc., 13, 323 (1864).
3. Philby, H. St.J. B., Geogr. J., 81, 1 (1933); “The Empty Quarter” (London, 1933). Spencer, L. J., with chemical analyses by Hey, M. H., Mineral. Mag., 23, 387 (1933).
4. King, E., “Stones said to have Fallen from the Clouds” (London, 1796); also included is a contemporary account of the fall of a stone [chondritic meteorite] weighing 56 lb. at Wold Cottage, Yorkshire, on December 13, 1795, thought to have condensed from clouds of volcanic dust wafted from Mt. Hekla.
5. Yavnel, A. A., Geokimiya, Acad. Sci. U.S.S.R., No. 6, 553 (1957).