Also, if this textbook is a local publication in the US or elsewhere, maybe it's not widely available in digital format. If Matias Arreola is a Mexican engineer, maybe the publication is in Spanish but the book mentioned is in English. Maybe the name is similar to another author I know.
The search for is understandable given the high cost of textbooks. However, the risks of piracy—legal, cybersecurity, and ethical—far outweigh the short-term savings. Arreola’s textbook remains a solid resource for learning how to apply economic logic to engineering decisions, but it is not irreplaceable. Engineering Economy 3rd Edition By Matias Arreola Pdf