1. Strughold H, Harber H, Buettner K, et al. Where does space begin? Functional concepts at the boundaries between atmosphere and space. J Aviat Med. 1951;22:342–9.
2. DeHart RL. The atmosphere. In: DeHart RL, editor. Fundamentals of aerospace medicine. 2nd ed. Philadelphia: Williams and Wilkins; 1996.
3. Emmert JT. A puzzling collapse of Earth’s upper atmosphere, 15 July 2010. NRL/NASA. Available from:
https://science.nasa.gov/science-news/science-at-nasa/2010/15jul_thermosphere/
.
4. Radiation penetrance values from NASA Goddard Space Flight Center;
http://www.theozonehole.com/images/atmosnasa.jpg
.
5. Humble RW, Henry GN, Larsen WJ. Introduction to space propulsion. In: Humble RW, Henry GN, Larsen WJ, editors. Space propulsion analysis and design. Reston: American Institute of Aeronautics and Astronautics; 1995.