1. The Foundations of Optics;Born,1973
2. The Propagation of Radio Waves in the Ionosphere;Budden,1985
3. The inhomogeneous structure of the upper ionosphere;Erukhimov,1980
4. The Saddle-Point Method;Fedoryuk,1977
5. Problems of Diffraction and Propagation of Electromagnetic Waves;Fock,1970