Here you can find the official whitepapers from each of the five privacy coins investigated. The whitepapers of each cryptocurrency were written by the developers of each coin and published to provide the public with a deep insight of the coin. The whitepapers proved to be an excellent source for the collection of historical background information, specific technology implemented, and the aims of each project.
Monero
https://www.getmonero.org/library/Zero-to-Monero-2-0-0.pdf
www.getmonero.org
Zcash
zerocash-project.org
zerocash-project.org
Dash
Whitepaper 路 dashpay/dash Wiki
Evan Duffield - evan@dash.org Daniel Diaz - daniel@dash.org Abstract. A cryptocurrency based on Bitcoin, the work of Satoshi Nakamoto, with various improvements such as a two-tier incentivized network, known as the masternode network. Included are other improvements such as PrivateSend, for increasing fungibility, and InstantSend, which allows instant transaction confirmation without a centralized authority.
github.com
Beam
docs.beam.mw
docs.beam.mw
PIVX
pivx.org
pivx.org