It's one of the first editions of the classical guide. At this moment there exists a fifth one. There is it's annotation:''An indispensable reference for aerospace designers, analysts and students.This fifth revised and enlarged edition of this classic, indispensable, and practical guide provides a condensed collection of commonly used engineering reference data specifically related to aerospace design. New material on air breathing propulsion, systems engineering, and radar cross section has been added to reflect recent data in aircraft design.''