My writeup: https://keithalewis.github.io/math/um.html for modeling and https://keithalewis.github.io/math/uf.html on now to more accurately reflect the real world. I have taught Derivative Securities at NYU, Columbia, Cornell, and Rutgers over the past 14 years, but my day job is turning math into software that produces numbers people running a business will pay for. The textbooks are missing some important things.