I saw this question, but I think the answer didn't fully address what I want to know about it:

Nash's paper on parabolic equations.

It says almost everything developed later in elliptic and parabolic equations depends on Di-Giorgi and Nash's work, but I haven't seen Nash's approach exposed nearly as frequently as De-Giorgi's in various books/lecture notes. So, my question is: Do you have a good reference for Nash's approach to his famous theorem **and** later developments based on that? **NOTE**: I'm not asking for Nash's own paper, which I already have. What I'm more interested in is an exposition with references to more recent developments.