Below you can find a couple of good posts by Murat on geo-replication for recent academic work. In particular, the first link has good explanation on Paxos optimizations.
MDCC: Multi-Data Center Consistency
Making Geo-Replicated Systems Fast as Possible, Consistent when Necessary
And, if you want to watch the OSDI presentation on the RedBlue consistency (second link above), click on this video link.