University of Chicago Press. 2008: 590. ISBN 978-0-226-59440-8. Plotner, Tammy. The Night Sky Companion: A Yearly Guide to Sky-Watching 2009. Springer...
physical media: Plotner, Tammy; Barbour, Jeff. What's Up 2006: 365 Days of Skywatching (PDF). 2006. ISBN 978-1-4116-8287-0. Plotner, Tammy. What's Up 2007: 365...