- Smart Bitcoin Investing Strategies https://www.smartbitcoininvestments.com
- Bitcoin Mining Difficulty https://bitcoinwisdom.com/bitcoin/difficulty
- Bitcoin Wiki https://en.bitcoin.it/wiki/Main_Page
- Bitcoin Original White Paper https://bitcoin.org/bitcoin.pdf
- Bitcoin Forum https://bitcointalk.org/index.php
- Bitcoin Related Hashes http://en.wikipedia.org/wiki/Cryptographic_hash
- Bitcoin Currency Improvements https://en.bitcoin.it/wiki/Bitcoin_Improvement_Proposals