Planisphere | freestarcharts.com,The Night Sky 30°-40° (Small) Star Finder: David S. Chandler, David Chandler Company, Milky Way by Don Davis: 9781891938023: Amazon.com: Books,Stars & Night Sky,南天に輝く銀河の四重奏 ぼうえんきょう座の相互作用銀河「NGC 6845」,40 Star charts Images: PICRYL - Public Domain Media Search Engine Public Domain Search