1949. Reprint. 36 pages. White and orange jacket over paperback book with matching paper covers. Contains some diagrams and graphs. Staple binding. Pages remain bright and clear. Binding is firm. Paper covers have minimal edgewear, with minor curling to corners. Minimal scuffing to spine ends. Rust marks surrounding staples. Noticeable white marks to front cover. Unclipped jacket. Visible rust marks to spine, with moderate sunning and scuffing. Minimal edgewear with slight creasing and minor chipping to spine ends.