One of the most popular books promoting traditional isometrics in the early 1960s was a book written by Henry Wittenburg. The book uses a variety of isometric exercise using a doorway, rope, or muscle pitted against muscle, combined with more traditional calisthenics (isotonic) exercises to provide strength and full-body fitness. The book is available free at the Sandow Plus website and is still a great read after all of these years -
http://www.sandowplus.co.uk/Competition/Wittenberg/Wittenberg%20Isometrics.pdf