McGraw-Hill is a major publishing house. They actively protect their intellectual property. A free, public domain PDF of the 2nd or 3rd edition does not legally exist. Most links claiming to offer the "Circuiti Elettrici Renzo Perfetti.pdf" for free are either scams, contain malware, or are incomplete photocopies of older editions.
The book "Circuiti Elettrici" by Renzo Perfetti is a significant resource for several reasons: Circuiti Elettrici Renzo Perfetti.pdf