Sams Publishing (now part of Pearson) holds the copyright. Most repositories hosting full PDFs of technical books are eventually taken down via DMCA (Digital Millennium Copyright Act) requests. If you do find a PDF on a random GitHub repo, there are risks:
Although some GitHub repositories occasionally host PDF versions of older books for archival or educational purposes, Sams Publishing and O'Reilly Media are the primary official platforms for digital access. Is it still relevant today? Carlos487/awesome-wpf - GitHub wpf 45 unleashed pdf github upd
: Explaining the backbone of WPF's data and property system. Sams Publishing (now part of Pearson) holds the copyright