1. Density of Neutral Gas in a Planetary Exosphere
2. Distribution of Density in a Planetary Exosphere
3. E. J. Öpik and S. F. Singer (to be published).
4. J. F. Herring (private communication received December 1, 1959) has kindly pointed out to us the omission of a factorvin the derivation of our Eq. (15) which is also mentioned in reference 1. The equation is given here in corrected form; see also reference 3.
5. Solar Emission Lines in the Extreme Ultraviolet.