From the reviews:

„The book is about sub-Laplacians on stratified Lie groups. The authors present the material using an elementary approach. They achieve the level of current research starting from the basic notions of differential geometry and Lie group theory. The book is full of extensive examples which illustrate the general problems and results. Exercises are included at the end of each chapter. … The book is clearly and carefully written. It will be useful for both the graduate student and researchers in different areas.“ (Roman Urban, Zentralblatt MATH, Vol. 1128 (6), 2008)

„The monograph under review is a comprehensive treatment of many interesting results regarding subelliptic partial differential equations. The first aim of this book is to give a complete overview on stratified Lie groups and their Lie algebras of left-invariant vector fields. … addressed to specialists in this area.“ (Maria Stella Fanciullo, Mathematical Reviews, Issue 2009 m)