Books
The DevOps Handbook.
Great read for everyone engaged in software development. Why DevOps is a philosophy, not another iteration of ITOps and how it can change your work. Rich in case studies.
Michal
The Pragmatic Programmer.
Amazing book written in 1999 by Andrew Hunt and David Thomas, revised for 20-th anniversary edition. How visionary they are you can realise when you compare both versions. Must read.