1. Bodman, H. v., Kolb, H. 1977: Gespräch der Deutschen Gesellschaft für Holzforschung (DGfH) am 11. Mai 1977 in Hamburg zum Thema “Maschinelle Holzsortierung (Stress grading)”, Unveröffentlichter Sitzungsbericht
2. Curry, W.T., Fewell, A.R. 1977: The relations between the ultimate tension and ultimate compression strength of timber and its modulus of elasticity. BRE Current Paper CP 22/77, 15 S.
3. Draper, N., Smith, H. 1966: Applied regression analysis, 407 S. New York: Wiley
4. Gerbards, C.C. 1972: Relationship of tensile strength of southern pine dimension lumber to inherent characteristics. U.S.D.A. Forest Service Research Paper FPL 174, 31 S.
5. Gerhards, C.C., Ethington, R.L. 1974: Evaluation of models for predicting tensile strength of 2-by 4-inch lumber. Forest Prod. J. 24 (12): 46–54