1969. First Edition. 114 pages. Paperback book with colourful paper covers. Contains black and white diagrams and graphs throughout. Pages remain bright and clear, with light tanning and foxing to textblock edges. Binding is firm. label and pencil inscription to reverses of front cover. Minimal edgewear to paper covers with minor curling to corners and mild scuffing to spine ends. Visible crease to front cover, causing corner to lift up.