Nice, to the point, book that explains vacuum tubes and their use in radio to beginners. Chapters are: The Electron, The Diode, The Triode, The Tetrode, The Pentode, Multipurpose Tubes, Phototubes and Indicator Tubes, Vacuum-Tube Grid Bias, and Radio-Tube Application. You get accurate and simple discussions on plate resistance, load lines, class A amplifiers, perveance, oscillators, cross-modulation, mixers and much more. Good introductory book on the subject. 96 pages with numerous circuit diagrams. Paperback. Lindsay Publications