1. Aggson, T. and Heppner, J. P.: 1965a, A Proposal for Electric Field Measurements on the Gravity-Gradient ATS-A Satellite. NASA GSFC, Febr. 1965.
2. Aggson, T. and Heppner, J. P.: 1965b, A Proposal for Electric Field Measurements on the Synchronous Orbit Gravity-Gradient Satellites ATS-D and E. NASA GSFC, Sept. 1965.
3. Aggson, T. and Heppner, J. P.: 1965c, A Proposal for Electric Field Measurements on POGO Satellites (OGO-D and OGO-F). NASA GSFC, Oct. 1965.
4. Alfvén, H.: 1967, Space Sci. Rev. 7, 140?148.
5. Al'pert, Y. L., Gurevich, A. V., and Pitaevskij, L. P.: 1965, Space Physics with Artificial Satellites. Consultants Bureau, New York.