I did my Master's degree in Systems Engineering based on both Haberfellner and Incose's handbook. It's been great learnings which have been useful ever since helping me to separate all kinds of problems as both a software developer and a systems architect.
You might find some of their handbooks online free of charge (maybe not the one most up-to-date).
There is a really good book written by Haberfellner called 'Systems Engineering' which to my knowledge is only available in German. The book is awesome though: https://www.amazon.de/Systems-Engineering-Grundlagen-Reinhar...
Oh, it seems like they finally managed to get it translated - apparently available in July this year: https://www.jpc.de/jpcng/books/detail/-/art/reinhard-haberfe...
I did my Master's degree in Systems Engineering based on both Haberfellner and Incose's handbook. It's been great learnings which have been useful ever since helping me to separate all kinds of problems as both a software developer and a systems architect.
So, enough said - separate and conquer ;)