The description of services presented in this chapter is quite complete, like the description of the Angular HttpClient object. A list of all method overloads may be found in the official documentation here: https://angular.io/api/common/http/HttpClient. More details on RxJS observables are available on the RxJS official website at https://rxjs-dev.firebaseapp.com.
All properties and methods of the Router object are available in the following Angular official documentation: https://angular.io/api/router/Router. The Testing section just describes the basics of Angular testing. Angular official documentation on testing contains detailed procedures to test any Angular class type (services, components, pipes, and so on): https://angular.io/guide/testing. Detailed documentation on end-to end testing with Protractor can be found on Protractor's official website...