Owning the file is 1% of the battle. Here is the 99%:

The Upstream Proficiency C2 Student’s Book PDF is legally available through authorized educational distributors (e.g., Express Publishing e-book store, VitalSource, or licensed ELT platforms). Always ensure you are accessing a legitimate copy to support the authors and publishers.

The book is meticulously aligned with the Cambridge C2 Proficiency (CPE) exam. It covers: