An Invitation to Hypoelliptic Operators and Hörmander's Vector Fields

From the book reviews:

“It represents a detailed survey of the theory of hypoelliptic operators and Hörmander’s vector fields, containing all the main results, from the first contributions in the late 1960s up to the most recent results. … a valuable guide to the literature of this field and will certainly be much appreciated by every Ph.D. student working in PDEs.” (Fabio Nicola, Mathematical Reviews, February, 2015)

“The text is a good introduction to the subject for those interested in this branch of the theory of partial differential equations. … It has plenty of examples that illustrate the topics being studied, mainly in the first chapters. … The book finishes with some more recent results that are set, in some way, in an extended class of Hörmander’s operators.” (Sérgio Luís Zani, zbMATH, Vol. 1298, 2014)