1. Gottlieb, D., Plant Disease Reptr. (U.S.) 29: 219 (1955).
2. Methods in plant physiology 1937
3. Ammann, A., Phytopathology 45: 559 (1954).
4. Zur Kenntnis der Phytosterine. Über das Hydro‐carotin
5. Elsevier's Encylopaedia of Organic Chemistry 1808 14