1971. Fourth edition. 200 pages. Pictorial dust jacket over blue cloth. Black and white photographs and diagrams. Pages remain bright and clean with minimal tanning and foxing. Binding remains firm. Boards have light shelf wear with minor corner bumping and crushing to spine ends. Some mild marks and staining to surfaces. Unclipped jacket has light edge wear with minor tears, chipping and creasing. Some rubbing and marking to surfaces.