Under KANT's deontology, an action is ethical if it produces a great amount of happiness, Since I make half of BOS happy ... I consider spreading resources ethical,
Well, I sell my maths notes and I don't use any images or anything like that to avoid situations like these. So everything I made in my notes is done by myself. However the content does overlap with well pretty much every book because no-one can really copyright maths. I make the example questions myself so they are tailored to the examples