The starting point for Bitcoin is the Whitepaper which was issued on 31 October 2008, it is only 9 pages long and can be found here. The paper was issued by a person or persons unknown going by the pseudonym of Satoshi Nakamoto, it is a technical work of genius. You can buy the T-shirt here (but only after you have read the paper!).
There are now many books seeking to explain Bitcoin, the two I recommend are Digital Gold, which is the backstory and history of the early days of Bitcoin, and The Bitcoin Standard, which is a very easy to read explanation of the technology of Bitcoin and how it sits within the history of money.
Good luck and enjoy!