1. Allen, C.W.: Astrophysical Quantities. Athlone, London (1973). Very useful table compilation of physical and astronomical data, constants and unit conversions. Table 2.2 is based on this reference. See also the recent revised version by Cox, A.N. (ed.). 2000. Allen’s Astrophysical Quantities. New York, American Institute of Physics/Springer
2. Gondhalekar, P.M.: The ultraviolet starlight in the Galaxy. In: Bowyer, S., Leinert, C. (eds.) IAU Symposium 139, p. 49. Kluwer, Dordrecht (1990). Updated discussion on the interstellar radiation field. Figure 2.2 is based on this reference
3. Kaplan, S.A., Pikelner, S.B.: The Interstellar Medium. Harvard University Press, Cambridge (1970). Referred to in chapter 1. Includes a discussion on the interstellar radiation field
4. Kolb, E.W., Turner, M.S.: The Early Universe. Addison-Wesley, Reading (1990). A good discussion on the early Universe, the Big Bang and the cosmic microwave background radiation
5. Lang, K.R.: Astrophysical Formulae. Springer, Berlin (1999). Updated compilation of astrophysical data, including detailed formulae of the principal physical processes mentioned in section 2.2