Does anyone knows what's the font used in Michael Spivak's "Calculus" and "Calculus on Manifolds" ? I think they're not the same font. The point is that they're both very good fonts, and I didn't find any information anywhere.
Can someone point out what fonts were used?
Edit: Bellow there's a screenshot of Calculus:

And bellow there's a screenshot of Calculus on Manifolds:
