1975. Sixth Impression. Unpaginated. Pictorial blue dust jacket over pictorial blue paper covered boards. Contains black and white in-text illustrations. Pages are lightly tanned and foxed throughout. Light thumb-marking present. Binding remains firm. Boards have mild edge wear with slight rubbing to surfaces. Soft crushing to spine ends. Clipped jacket has moderate edge wear with chips, tears and creasing. White sticker to front panel, with ring shaped water staining.