(Recommended)
Leslie Lamport. Paxos Made Simple. 2001.
Burrows, Mike. The Chubby lock service for loosely-coupled distributed systems. OSDI 2006.
(Optional)
Tushar Chandra, Robert Grisemer, and Joshua Redstone. Paxos Made Live – An Engineering Perpective. PODC 2007.
Leslie Lamport. The Part-time Parliament. ACM Transactions on Comput. Sys. 1998.
Diego Ongaro and John Ousterhout. In Search of an Understandable Consensus Algorithm. 2014.
Flavio P. Junqueira, Benjamin C. Reed, and Marco Serafini. Zab: High-performance broadcast for primary-backup systems. DISC 2009.