Now, the user is asking for a PDF link. Legally, that's a problem because most textbooks, especially those part of educational course series, are protected by copyright. Distributing or sharing such PDFs without the publisher's permission is a violation of copyright law. I should make sure not to facilitate any illegal sharing.
Let me structure the response. Start by acknowledging the request, then explain the legal issues, suggest legal alternatives like purchasing, checking with libraries, and using official resources. Also, offer to help with other related queries if needed.
Also, consider that if someone is looking for a PDF link, they might be looking for study materials, but without legal means. Emphasize the importance of respecting copyright. Maybe offer to help with other resources they can legally access, like YouTube tutorials, online grammar exercises, or other free German learning materials.