DISTRIBUTED SYSTEMS: CLOCK SYNCHRONISATION

T. K. Srikanth and Sam Toueg: Optimal clock synchronization. Journal of the ACM, volume 34, issue 3, July 1987. Pages 626–645.
Flaviu Cristian: Probabilistic clock synchronization. Distributed computing, volume 3, 1989. Pages 146–158.
L. Lamport and P. M. Melliar-Smith: Synchronizing clocks in the presence of faults. Journal of the ACM, volume 32, issue 1, January 1985. Pages 52–78.