This book makes life easier for all mathematicians interested in quasiconformal theory and all its generalisations, analysis of mappings between Euclidean spaces or manifolds, and all related areas ... The book is well written and may comfortably be read by advanced students. EMS The book begins with an expertly written overview, which will be of value even to specialists in the field ... authoritatively written by two of the leading figures in the field ... contains a wealth of material ... makes pleasant reading. Bulletin of the London Mathematical Society