Equatorial Pitch Angle Distributions of 1-50 keV Electrons in Earth's Inner Magnetosphere: An Empirical Model Based on the Van Allen Probes Observations. - Zhao, H.; Friedel, R. H. W.; Chen, Y.; Baker, D. N.; Li, X.; Malaspina, D. M.; Larsen, B. A.; Skoug, R. M.; Funsten, H. O.; Reeves, G. D.; Boyd, A. J. (Journal of Geophysical Research. Space Physics, 2021)