The following three texts are strongly reccommended:
Note that the third is available online*. Your local library should have copies of the other two. If they're out, request that the book(s) be put on hold for you. If that library branch doesn't have any copies of a book that you would like to read, request one. The book will be moved from another library over to your local one.
The above books were chosen because they provide the groundworks for good comic drawing, and good drawing in general. The Scott McCloud one is a comic book that explains comic books. A must read for any aspiring comic book writer or artist. The Betty Edwards one gives lessons on how to use the right side of your brain to draw, rather than the left side. Using the right side is vital for making good drawings. The Loomis one was chosen primarily because it is available online. However, the book is excellent. It explains the methods used to draw, and doubles as a quick anatomy reference. This book does contain nudity, but you have to look at naked people to learn how to draw humans. That's just the way it works.
The below books are all very good. They're not worse than the books above, but they tend to be more specific to a certain topic. We'd suggest reading them all over a period of one or two years.
* To the best of my knowledge, this is not 'pirated' or whatnot. If this is not so, let me know.