Chapter 11, page 232, states we ‘should follow the installation instructions found in chapter 8, “RESTful Networking” to install Vapor.’ A search of “Vapor” in the book only yield page 232, chapter 8 does not reference Vapor.
Also, chapter 8 is called “Networking client” (might want to make that a cap “C” on “client” to be consistent with other chapters) not “RESTful Networking”, nor is there any subhead "RESTful Networking.
On page 239, it states '“Restful Networking”, covers the theories and strategies for how to do this." Is that also referring to chapter 8? If so, you might want to change that and clarify it refers to chapter 8.