Skinner, W.R., P.B. Hays, M.D. Burrage, D.A. Gell, A.R. Marshall, and H.J. Grassl, “The High Resolution Doppler Imager: Instrument performance in orbit since late 1991,” SPIE: Optical Science, Engineering, and Instrumentation, Denver ‘96 Symposium, Denver, CO, August, 1996.