Ask HN: What are some good data synchronization implementation references?

I am interested in mastering the concepts and best practices needed to implement data synchronization well, in apps that require this functionality. Are there specialized books that cover this, or other helpful resources? How about generalized synchronization libraries that can do the heavy lifting (though I'd still like to know the important concepts myself as well)?

I'm sure there's some overlap with version control system design, but maybe synchronization is a broader field than I imagine.