1. Cheng , Z. S. A. Cummer 2002 Multi-path D region ionosphere remote sensing NSF CEDAR Workshop Longmont, Colo.
2. Relations among low ionospheric parameters and A3 radio wave absorption;Cipriano;J. Geophys. Res.,1974
3. The Schumann resonances;Cole;J. Res. Natl. Bur. Stand. U.S., Sect. D,1965
4. Electrification in the Earth's atmosphere for altitude between 0 and 100 km;Cole;J. Geophys. Res,1965
5. Cummer , S. A. 1997 Lightning and ionospheric remote sensing using VLF/ELF radio atmospherics Dep. of Electr. Eng., Stanford Univ. Stanford, Calif.