1. Bolza, O.: Lectures on the Calculus of Variations, third edn. Chelsea, New York (1973)
2. Born, M.: Untersuchungen über die Stabilität der elastischen Linie in Ebene und Raum, unter verschiedenen Grenzbedingungen. Dieterichsche Universitäts-Buchdruckerei, Göttingen (1906)
3. Brechtken-Manderscheid, U.: Introduction to the Calculus of Variations. Chapman & Hall, London (1991). Translated from German by P. G. Engstrom
4. Crespo da Silva, M.R.M., Glynn, C.C.: Nonlinear flexural-flexural-torsional dynamics of inextensional beams. I. Equations of motion. Journal of Structural Mechanics 6 (4), 437–448 (1978). URL http://dx.doi.org/10.1080/03601217808907348
5. Euler, L.: Methodus Inveniendi Lineas Curvas Maximi Minimive Proprietate Gaudentes, sive Solutio Problematis Isoperimetrici Lattissimo Sensu Accepti: Additamentum 1 De Curvis Elasticis. Leonhardi Euleri Opera Omnia, Series prima (Opera mathematica), Vol. XXIV, Auctoritate et impensis Societatis Scientiarum Naturalium Helveticae. Orell Füssli, Zürich (1952). An English translation of this work can be found in [254].