Boehnhardt, H., Birkle, K., Fiedler, A., Jorda, L., Peschke, S., Rauer, H., et al. (1999). Dust morphology of comet Hale-Bopp (C/1995 01): I. Pre-perihelion coma structures in 1996. Earth, Moon and Planets, 78, 179-187.