1. Bleich F. Buckling Strength of Metal Structures McGraw‐Hill Book Co. Inc. New York N.Y. 1952.
2. Fung Y. C. Foundations of Solid Mechanics Prentice Hall Inc. Englewood Cliffs N.J. 1965 pp. 463–465.
3. Gjelsvik A. The Theory of Thin Walled Bars John Wiley and Sons Inc. New York N.Y. 1981 p. 198.