Over 900 color figures are used. 
Color adds a dimension to figures that improves comprehension.
For instructional use, I have prepared color editions of
Klystrons, Traveling Wave Tubes, Magnetrons,
 Crossed-Field Amplifiers and Gyrotrons
Klystrons, Traveling Wave Tubes, Magnetrons,
 Crossed-Field Amplifiers and Gyrotrons
Color Edition
For use in class rooms, a 3-ring notebook format is used rather than
 a hardcover bound format 
Because of the large size, the latest version has been divided into two volumes.

                                       Hardcover                     Notebook