Authors sometimes allow free downloads for early drafts. Search Leanpub for "PHP 7 Algorithms" and set the price to $0. You get a high-quality, DRM-free PDF directly.
You’ve found a candidate PDF. Is it the "best work" ? Run this 3-point check:
A PDF is only "the best work" if it focuses on practical complexity analysis (Big O) for web contexts:
Instead of hunting for a PDF, clone these repos and read the code: