1952
Bibliografía (5 obras)
Guía de observatión del maratón Messier
2003
The Observing Guide to the Messier Marathon
2002
An observer's guide to comet Hale-Bopp: Making the most of Comet Hale-Bopp
1996
Messier marathon observer's guide
1994
A decade of comets
1985
