The AUTOSAR (AUTomotive Open System ARchitecture) Compendium serves as a comprehensive guide to the global development standard for automotive software. specifically focuses on the upper layers of the stack:
Having a local copy ensures that you can reference complex diagrams even without a stable internet connection.
If you are looking for the technical details regarding the Application Layer and RTE (Runtime Environment) without the specific commentary found in the Compendium, you can download the official specifications for free from the AUTOSAR organization.