1. Darrow, G. M, andWaldo, G. F. (1934). Responses of strawberry varieties and species to the duration of the daily light period. U.S.D.A. Tech. Bull., 453.
2. Hill, H., andDavis, M. B. (1929). Studies in strawberry bud differentiation. Dominion of Canada Dept, of Agric. Bull. 110. N.S.
3. James, W. O. (1936). Plant Physiology (3rd edition).