What’s the most reliable way to find everything a specific expert has said about a topic without AI hallucinations?

A user is seeking the most reliable method to find everything a specific expert has said about a particular topic, explicitly aiming to avoid AI hallucinations. The core problem is framed as answering the question: "What has [Expert X] said about [Topic Y]?" The user is optimizing for minimum hallucination and maximum source coverage in the design of such a solution.