Add two nice reference books to your library very inexpensively.
1. Atlas of Deep Sky Splendors by Hans Vehrenberg. 242 pages. High quality wide-field photo charts covering over 400 deep sky objects. Limiting mag is 17. Good condition in dust jacket. $ 20.00. Price includes shipping.
2. Atlas of the Sky by Vincent de Callatay. Series of plates. Not charts, but instead are in the nature of representations of the sky with stars depicted as white spots on a black background with the size of the stars per their brightness in the sky. 156 pages. Good condition. $ 15.00. Price includes shipping.