Since I am going to join Prof. Shaul Mukamel group soon, I recently read his book  “Principles of nonlinear optical spectroscopy” again. This is an excellent book for nonlinear spectroscopy in molecules. Although I do think it is a little bit technical in the sense that it goes into the third-order dipole response functions w.r.t. the external electric field. But after getting some familiarity with the mathematical language (i.e. Liouville space pathways), it becomes a wonderful reading experience.