# Citations
The following list is composed of the sources we used to build this
chapter. We deem these sources credible. Reference style is APA.
* Antonopoulos, A. M. (2014). Mastering Bitcoin: Unlocking Digital Cryptocurrencies (1st ed.). O’Reilly Media.
* Antonopoulos, A. M., & Wood, G. (2018). Mastering Ethereum (1st ed.). Van Duuren Media.
* Wagner, L. (2021, October 20). How SHA-256 Works Step-By-Step. Qvault. Retrieved January 9, 2022, from https://qvault.io/cryptography/how-sha-2-works-step-by-step-sha-256/
* Turner, D. M. (2020, January 23). SHA-1 is Practical and Cost-Effective to Crack Now. Cryptomathic. Retrieved January 9, 2022, from https://www.cryptomathic.com/news-events/blog/sha-1-is-practical-and-cost-effective-to-crack-now
* 손. (2021, December 9). Bitcoin#6: Target and Difficulty - 손동하. Medium. Retrieved January 9, 2022, from https://medium.com/@dongha.sohn/bitcoin-6-target-and-difficulty-ee3bc9cc5962
* Chapter 1. Introduction to Public-Key Cryptography Red Hat Certificate System 9. (n.d.). Red Hat Customer Portal. Retrieved January 9, 2022, from https://access.redhat.com/documentation/en-us/red_hat_certificate_system/9/html/planning_installation_and_deployment_guide/introduction_to_public_key_cryptography
* Champagne, P. (2014). The Book of Satoshi: The Collected Writings of Bitcoin Creator Satoshi Nakamoto. e53 Publishing LLC.
* V. (2018, June 7). Technology Primer part 1: RSA encryption - Viacoin. Medium. Retrieved January 9, 2022, from https://medium.com/@viacoin/techology-primer-part-1-rsa-encryption-b98be35e189f
* Nakamoto, S. (2008, October). Bitcoin: A Peer-to-Peer Electronic Cash System. Satoshi Nakamoto. https://bitcoin.org/bitcoin.pdf