In statement of purpose, good to mention about learning from some professor's lecture notes and books?
You do not want to convey the message, "I am applying to your school because I think Professor X is great."  Everybody knows Professor X is great.  That's why they hired her.

The question is, why should they want you?

A message you do want to convey is, "I am applying to your school because my research goals are well-aligned with existing interests in the department."  If you can incorporate Professor X's notes and books into that story, great.  Otherwise, leave them out of it.