Modell 21 is found on pp. 26-27. The chart, located on p. 27, is incorrectly labeled as Modell 22. The correct chart is the top chart located on the center right of p.27. The chart itself, however, is error-free. The glossary of chart symbols is located on p. 18. The notation used by Lea is quite different from that found in most other US or German publications. It is not as intuitive as others, so caution is advised.