"For anyone interested in the rapidly developing field of string theory (graduate students with the proper physics background), Siegel's book is a particularly good introduction."
Choice, USA

"Siegel has played a major role in the application of BRST formalisms for quantization to string theory ... Siegel's book is of great interest for those who intend to do research in string field theory."
Foundations of Physics, USA
This volume covers the most up-to-date findings on string field theory. It is presented in a new approach as a result of insights gained from the theory. This includes the use of a universal method for treating free field theories, which allows the derivation of a single, simple, free, local, Poincare-invariant, gauge-invariant action that can be applied directly to any fields.