1. S. Chandrasekhar, Radiative Transfer, Oxford Univ. Press (1950).
2. V. V. Sobolev, Transfer of Radiative Energy in the Atmospheres of Stars and Planets [in Russian], Gostekhizdat (1956).
3. G. M. Wing, An Introduction to Transport Theory, Wiley (1962).
4. V. G. Gorbatskii and I. N. Minin, Nonstationary Stars [in Russian], Fizmatgiz, Moscow (1963).
5. R. E. Bellman, H. H. Kagiwada, R. Kalaba, and M. C. Prestrud, Invariant Imbedding and Time-Dependent Transport Processes, Am. Elsevier (1964).