1970. Third Edition. 188 pages. No dust jacket. Illustrated paper covered boards. Pages remain clear with minimal tanning and foxing. Tape marks to end papers and paste downs. Scuff marks to pre lims. Some occasional mild cracking to gutters throughout, binding remains reasonably firm. Boards have moderate edge-wear with bumping to corners and rubbing to surfaces. Mild crushing to spine ends. Book has a slight forward lean.