Robert J. Braidwood, Prehistoric Men (7th ed.; Glenview, Ill.: Scott, Foresman, 1967), pp. 81–153. On the physical conditions disposing the neolithic revolution to occur where it did in the ancient Near East, consult K. W. Butzer, The Cambridge Ancient History, 3rd ed. Vol 1/Part 1, 1976, pp. 35–62.