"The book emphasizes techniques of two-dimensional conformal field theory as the basis for perturbative string theory. . the book is a welcome (re-)addition to the growing collection of textbooks on string theory, and one that likely will be consulted whenever future generations return to the foundations of the subject. It is totally suited for a course in string theory straddling the undergraduate and graduate level. The occasional mathematician with a physics inclination will also find the book accessible." (Johannes Walcher, Mathematical Reviews, January, 2014)

"This book is amazing! The author presents the string theory in a very pedagogical way. . The book contains a lot of examples and problems and it is a easy reading. . I recommend this book for instructors and students interested in understand the basic principles of string theory. This book will be very useful as a additional reading for more advanced courses in string theory too! Have fun!" (Philosophy, Religion and Science Book Reviews, bookinspections.wordpress.com, December, 2013)