Anything you can get your hands on written by Gerald Weinberg.

This is a good place to start:

https://www.amazon.co.uk/Quality-Software-Management-Systems...

They’re all available as ebooks as well, I think the QSM series was split up and went on to become this:

https://leanpub.com/b/qualitysoftware

And then these ones have the same titles as their paperback counterparts:

https://leanpub.com/b/peopleskillssoftbutdifficult