Grego, Peter (2008). "Recording Mercury and Venus". Venus and Mercury, and How to Observe Them. Astronomers’ Observing Guides. New York, NY.: Springer. pp. 177–206. doi:10.1007/978-0-387-74286-1_5. ISBN978-0-387-74285-4.
Marsden, B. G. (1994). Milani, Andrea; Di Martino, Michel; Cellino, A. (eds.). Search Programs for Comets. Asteroids, Comets, Meteors 1993: Proceedings of the 160th Symposium of the International Astronomical Union, held in Belgirate, Italy, June 14-18, 1993. International Astronomical Union. Symposium no. 160. Dordrecht: Kluwer Academic Publishers. p. 1. Bibcode:1994IAUS..160....1M.