1. Chaplin, New Intl. Assn. of Testing Materials, 1931, Zurich.
2. Wilson, U.S. Dept. of Agr. Bulletin No. 282, March 1932.
3. Unpublished data by F.P.R.L. on Sitka Spruce.
4. Barkas, NATURE, 130, 699; 1932.
5. Urquhart and Williams, Shirley Inst. Mem., 3, 197; 1924.