1968. First Edition. 135 pages. This is an ex-Library book. Illustrated dust jacket over purple cloth. Expected library inserts, stamps and inscriptions. Black and white diagrams throughout. Pages remain clear with minimal tanning and foxing. Library plates, stickers and inscriptions to front free end-paper and paste-down. Library ink stamp to half-title page both paste downs. Binding remains firm. Boards have mild edge-wear with slight rubbing to surfaces. Damp staining to both boards. Unclipped jacket has light edge-wear with tears and creasing. Library sticker taped to spine edge.