Astronomy: A Visual Guide by Ian Ridpath. A very good and comprehensive guide for beginners, including types of telescopes and how to navigate the sky. Has info on both northern and southern hemispheres.
Choosing and Using Astronomical Eyepieces by William Paolini. A great resource for going about purchasing the best eyepiece for your needs. For both beginners and expert amateurs alike.
The Patrick Moore Practical Astronomy Series. Anything by Patrick Moore is an absolute must-have. All of his books are beautifully written and easy to understand.
50 Things to See With a Small Telescope (Southern Hemisphere ed) by John A Read. A very good resource if you are just starting out but aren’t sure where to start.
The One Minute Astronomer. This has some good recommendations on where to get started and ideas for your next star gazing session.
Spectroscopy:
Spectral Atlas for Amateur Astronomers by Richard Walker. A Guide to the Spectra of Astronomical Objects and Terrestrial Light Sources.
