Downloading a copyrighted textbook like Harper's Illustrated Biochemistry, 31st Edition from unauthorized websites is generally considered illegal copyright infringement . Under laws such as the U.S. Copyright Act

With the digital version in hand, Alex began to study with renewed enthusiasm. The clear explanations, accompanied by illustrations and diagrams, made complex biochemical concepts more accessible. He devoured the chapters, highlighting key points and making notes in the digital margins.

Harper's Illustrated Biochemistry, 28th Edition (LANGE Basic Science)