Ask HN: What are some other books as fundamental as DDIA?

There seem to be no doubts regarding the quality and importance of DDIA for backend engineers. I keep rereading particular chapters over and over again and there are new things for me every time depending on what I encountered and thought about at work.<p>What are some really important and fundamental books especially for backend engineers that you consider to be at least close in quality to DDIA?<p>I often suffer from analysis paralysis so I whatever you come up with here, I will read within the next few months :)