Google cloud messaging - Developing Android Apps

Migrate from Google Cloud Messaging to Firebase Cloud Messaging - Firecasts

Credentials for Google Cloud Messaging

Push Notification in Android Using GCM (Google Cloud Messaging)

Introducing Firebase Cloud Messaging

Firebase on Android: Cloud Messaging, Cloud Functions, Crashlytics

Setting up your Devices for Android Push Notification application development

Android Push Notifications using Google Cloud Messaging (GCM)