This free Udacity course by Google covers intro to PWAs, service workers and web app manifests
Open-Awesome is built by the community, for the community. Submit a project, suggest an awesome list, or help improve the catalog on GitHub.
An introduction to progressive web apps by Alex Russell and Andreas Bovens
Using Polymer to build progressive web apps
A great Udacity course introducing service workers and IndexedDB
A quick dive into the most common technologies and techniques for building progressive web apps