1975. Sixth Printing. 127 pages. Pictorial jacket over blue paper covered boards. Contains black and white photographs and diagrams throughout. Pages remain bright and clear. A few noticeable marks throughout. Binding is firm. Boards and spine have minimal shelf-wear, with mild corner bumping and crushing to ends. Moderate rubbing and scuffing overall, with small but visible marks also. Unclipped jacket. Light tanning to all surfaces, heaviest to spine and edges. Visible water staining to spine. Panels have light edgewear, with small tears, chips and creases, heavier to spine ends.