My first introduction to large scale development.
When I was 16 years old I borrowed this book from our neighbor next door. I brought it on vacation in France, and still remember the smell of fresh cut grass when I was reading this book in France, over and over again. The Appendix contained the entire source code of Minix.
Years later when I did my Master's Degree in Amsterdam I followed two courses by the author, Andrew Tanenbaum.