If you cannot find the official , you have two powerful alternatives.
The manual acts as a reversible vs. irreversible process . Used reversibly (study, then solve alone), it increases learning. Used irreversibly (copy only), it destroys knowledge. If you cannot find the official , you
Attempt a problem for at least 45 minutes. If you cannot start it, or if you hit a wall at a specific calculation (e.g., calculating total pressure recovery across an oblique shock), then open the manual. If you cannot find the official