1. Luyet, B. J., and Menz, L. J., Biodynamica, 7, 25 (1951).
2. Asahina, E., Low Temp. Sci., 10, 81 (1953).
3. Luyet, B. J., and Rapatz, G., Biodynamica, 8, 1 (1958).
4. Asahina, E., Contr. Inst. Low Temp. Sci., 10, 83 (1956).
5. Levitt, J., The Hardiness of Plant (Acad. Press, N.Y., 1956).