Quasistatic electric field measurements with spherical double probes on the GEOS and ISEE satellites - Pedersen, A.; Cattell, C. A.; Fälthammar, C. -G.; Formisano, V.; Lindqvist, P. -A.; Mozer, F.; Torbert, R. (Springer, 1984)
http://dx.doi.org/10.1007/BF00226365
Keywords: U