@article{03685720, title = {Projection operator techniques in Lagrangian mechanics: Symmetrically coupled oscillators.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {3}, year = {1980}, pages = {369-382}, doi = {10.1155/S0161171280000257}, zbl = {0439.20008}, language = {en}, url = {http://dml.mathdoc.fr/item/03685720} }
Boyd, J.N.; Raychowdhury, P.N. Projection operator techniques in Lagrangian mechanics: Symmetrically coupled oscillators.. International Journal of Mathematics and Mathematical Sciences, Tome 3 (1980) pp. 369-382. doi : 10.1155/S0161171280000257. http://gdmltest.u-ga.fr/item/03685720/