The American Mathematical Society (AMS) sells the official second edition in both Hardcover and eBook formats.

For by Patrick M. Fitzpatrick, you can find the textbook, solution manuals, and academic study guides through the following verified digital sources: 1. Textbook Access (PDF & Online View)

"Advanced Calculus" by Patrick M. Fitzpatrick is a comprehensive textbook that provides a rigorous and in-depth introduction to advanced calculus. The book is suitable for undergraduate students who have completed a standard calculus course and want to further develop their mathematical skills. While the book assumes a strong background in calculus, it provides a clear and concise exposition, comprehensive coverage, and an abundance of examples and exercises.

While not strictly "free" in the pirate sense, the Internet Archive’s frequently has a digitized copy of Fitzpatrick’s text. You can "borrow" the PDF for 1 hour or 14 days via controlled digital lending. This is legal, safe, and requires only a free account.

Here is the proper information regarding the book and how to find it.

: The 2nd edition of the textbook (2009) is officially cited and archived in repositories like Library & Institutional Access