The Elastic Stack used to be called the ELK Stack; this link provides more information.
Applied Network Security Monitoring: Collection, Detection, and Analysis by Chris Sanders and Jason Smith
The Art of Monitoring by James Turnbull
ElasticSearch 5.0 Cookbook - Third Edition by Alberto Paro
Elasticsearch Blueprints by Vineeth Mohan
Elasticsearch: A Complete Guide by Bharvi Dixit, Rafal Kuc, Marek Rogozinski and Saurabh Chhajed
ElasticSearch Cookbook, Second Edition by Alberto Paro
Elasticsearch: The Definitive Guide: A Distributed Real-Time Search and Analytics Engine by Clinton Gormley and Zachary Tong
Elasticsearch Essentials by Bharvi Dixit
Elasticsearch for Hadoop by Vishal Shukla
Elasticsearch in Action by Radu Gheorghe, Matthew Lee Hinman and Roy Russo
ElasticSearch Indexing by Huseyin Akdogan
ElasticSearch Quick Start: An introduction to ElasticSearch in tutorial form. by Joel Abrahamsson
Elasticsearch Server - Third Edition by Rafal Kuc and Marek Rogozinski
Kibana Essentials by Yuvraj Gupta
Learning Elasticsearch by Abhishek Andhavarapu
Learning ELK Stack by Saurabh Chhajed
Learning Kibana 5.0 by Bahaaldine Azarmi
The Logstash Book by James Turnbull
Mastering ElasticSearch 5.0 - Third Edition by Bharvi Dixit
Mastering Elasticsearch, Second Edition by Rafal Kuc and Marek Rogozinski
Monitoring ElasticSearch by Dan Noble
NoSQL Injection for Elasticsearch by Gary Drocella
Relevant Search: With applications for Solr and Elasticsearch by Doug Turnbull and John Berryman