Next, legal considerations. I can't distribute copyrighted material. So even if the user is asking for a free PDF, I can't provide a direct link. But maybe there are legitimate sources where they can access it for free, like Project Gutenberg or Google Books. However, if the book is not public domain, these sites might not have it. I should also check whether the book is still under copyright. Amit Goswami's book, for example, is likely still under copyright. So any free PDF would be illegal to distribute.