1. Wagner, H.: Verdrehung und Knickung von offenen Profilen. 25th. Aniversary Publication, Techn. Hochschule Danzig, 1904?1929, S. 329?343. Translated in NACA Tech. Mem. 807, 1936.
2. Bleich, F., Bleich, H.: Bending, Torsion, and Buckling of Bars Composed of Thin Walls. Prelim. Pub. 2nd Cong. Intern. Assoc. Bridge and Structural Eng., English Edition 1936, p. 871.
3. Kappus, R.: Drillknicken zentrisch gedrückter Stäbe mit offenem Profil im elastischen Bereich. Luftfahrt-Forschung 14 (1937) S. 444?457. Translated in NACA Tech. Mem. 851, 1938.
4. Goodier, J. N.: The Buckling of Compressed Bars by Torsion and Flexure. Cornell Univ. Eng. Expt. Sta. Bull. 27, 1941.
5. Timoshenko, S.: Theory of Bending, Torsion and Buckling of Thin-Walled Member of Open Cross Section. J. Franklin Inst. 239 (1945) p. 201; p. 249; p. 343.