Machholz, D. (2013). The observing guide to the Messier marathon: Ahandbook and atlas. Cambridge University.
Chicago Style aipamenaMachholz, Don. The Observing Guide to the Messier Marathon: Ahandbook and Atlas. Cambridge University, 2013.
MLA aipamenaMachholz, Don. The Observing Guide to the Messier Marathon: Ahandbook and Atlas. Cambridge University, 2013.
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