1968. Third Edition. 103 pages. Yellow jacket over green cloth with gilt lettering to spine. Photographs and diagrams throughout, in both colour and black and white. Pages are lightly tanned, but text remains clear. Binding is firm. Colour-coded annotations and underlining to some pages throughout. Previous owner's inscription to front pastedown. Boards and spine have minimal shelf-wear, with mild corner bumping and crushing to ends. Gilt remains bright. Boards are slightly warped. Unclipped jacket. Moderate marking overall. Panels have light edgewear, with small tears, chips and creases, heavier to spine ends. Visible tearing bewteen left flap and front panel.