Late in 2015, there were three new or updated books published about Couchbase that you need.

The first is Pro Couchbase Server 2nd ed. by Couchbase's own David Ostrovsky and Mohammed Haji, as well as Yaniv Rodenski. It is 349 pages of pure goodness. Published by Apress.

The second is Learning Couchbase by Henry Potsangbam. Published by Packt Publishing.

Last, but not least is, Pro Couchbase Development: A NoSQL Platform for the Enterprise by Deepak Vohra. Published by Apress.