Crovisier, J., Brooke, T. Y., Hanner, M. S., Keller, H. U., Lamy, P. L., Altieri, B., et al. (1996). The infrared spectrum of comet C/1995 O1 (Hale-Bopp) at 4.6 AU from the Sun. Astronomy and Astrophysics, 315, L385-L388.