“Notably, each chapter ends with a (shorter or longer) list of exercises complementing the material of the book as well as with some useful historical and bibliographical remarks. … The book is well written, and takes readers thoroughly into the theory of extending modules and their generalizations. I consider this volume a valuable tool and source of inspiration both for students interested in future research in an active field of algebra and for working researchers.” (Septimiu Crivei, Mathematical Reviews, May, 2017)“The book is addressed to students and researchers in module and ring theory. It will undoubtedly be a valuable tool for everybody working in this area. Finally, it should be mentioned that the authors have made a well-thought-out effort to improve and refine the terminology on the subject.” (Bin Zhu, zbMATH 1368.16002, 2017)