Déctor, A.; Morales-Técotl, H. A.; Urrutia, L. F.; Vergara, J. D. An alternative canonical approach to the ghost problem in a complexified extension of the Pais-Uhlenbeck oscillator. (English) Zbl 1208.81111 SIGMA, Symmetry Integrability Geom. Methods Appl. 5, Paper 053, 22 p. (2009). MSC: 81R12 70H15 37J15 PDFBibTeX XMLCite \textit{A. Déctor} et al., SIGMA, Symmetry Integrability Geom. Methods Appl. 5, Paper 053, 22 p. (2009; Zbl 1208.81111) Full Text: DOI arXiv EuDML
Hojman, Sergio; Urrutia, Luis F. On the inverse problem of the calculus of variations. (English) Zbl 0475.70023 J. Math. Phys. 22, 1896-1903 (1981). MSC: 70H03 37J99 49S05 70G10 PDFBibTeX XMLCite \textit{S. Hojman} and \textit{L. F. Urrutia}, J. Math. Phys. 22, 1896--1903 (1981; Zbl 0475.70023) Full Text: DOI