1970. No Edition Stated. 63 pages. This is an ex-Library book. Paperback book with pictorial paper covers. Staple bindning. Contains black and white diagrams and photographic plates throughout. Pages and plates remain bright and clear. Binding is firm. Paper covers have minimal edgewear, with minor curling and creasing to corners. Label and paper remnants to front cover, with more remnants to rear. Light rubbing overall.