Both books are like textbooks, but for courses not taught anywhere yet, because they are my discoveries.

But one of the books sells indeed, and it is not one I would expect to sell well.

But my other book "Algebraic Theory of General Topology" does sell, despite in a sense it is even more niche.

I also did try to do a Google Ads marketing campaign for Discontinuous Analysis. But it doesn't sell and I don't know why.

Please explain why my book Discontinuous Analysis https://teachsector.com/discontinuous-analysis/ (about the discontinuous variant of calculus rather than analyzing only continuous and smooth functions) does not sell.

Contrary to my expectation to be one of the best sellers among my books, this ...