1. Die altitudine colomnarum sub proprio pondere corruentium;Euler;Acta Acad Petropol,1778
2. Determination of the greatest height consistent with stability that a vertical pole on mast can be made and of the greatest height to which a tree of given proportions can grow;Greenhill;Proceedings of the Cambridge Philosophical Society IV,1883
3. Design of columns of varying cross-section;Dinnik;Transactions of the ASME,1929
4. Mathematical Methods in Engineering;Karman,1940
5. Theory of Elastic Stability;Timoshenko,1961