From the reviews: „This book (...) defines the boundaries of the subject now called combinatorial group theory. (...)it is a considerable achievement to have concentrated a survey of the subject into 339 pages. This includes a substantial and useful bibliography; (over 1100 items). ... the book is a valuable and welcome addition to the literature, containing many results not previously available in a book. It will undoubtedly become a standard reference.“ Mathematical Reviews, AMS, 1979 „This is a reprint of the 1977 edition … of this famous and very popular book, which became a desk copy for everybody who is dealing with combinatorial group theory. The complete bibliography (more than 1000 titles) well reflects the situation in the combinatorial group theory at the time when the book was published. Definitely, since the face of combinatorial group theory has significantly changed … this well-written book still is very functional and efficient.“ (Igor Subbotin, Zentralblatt MATH, Vol. 997 (22), 2002)