Links and goodness to go along with the eBook:

AWS Glossary - All things AWS here to help you learn nomenclature and definitions - https://docs.aws.amazon.com/general/latest/gr/glos-chap.html

AWS whitepapers - Great guides including the security and WAF guide which are must-reads both for day-to-day operations and especially if you want to get certified on AWS - https://aws.amazon.com/whitepapers/

We discuss many features of networking and security in brief.  There are some content areas that did not get covered due to the page count, so I highly recommend digging in on these:

Network ACLs - These are important for protection your cloud assets.  Blogs coming on these and more to target the more granular controls available with NACLs - https://docs.aws.amazon.com/vpc/latest/userguide/vpc-network-acls.html

Recommended NACLs - Simple guide with the top-recommended rules to apply based on a few common scenarios - https://docs.aws.amazon.com/vpc/latest/userguide/vpc-recommended-nacl-rules.html 

EC2 Instances at EC2Instances.info - a nifty resource that is maintained online to highlight differences in features in EC2 - https://ec2instances.info