There are multiple whitepapers for this project:
– Ouroboros A Provably Secure Proof-of-Stake Blockchain Protocol
– Ouroboros Praos – An adaptively-secure, semi-synchronous proof-of-stake protocol
– Kaleidoscope – An Efficient Poker Protocol with Payment Distribution and Penalty Enforcement
– SCRAPE – Scalable Randomness Attested by Public Entities
– Sidechains – Non-interactive proofs of proof-of-work
See the link below for all whitepapers concerning Cardano.