@article{02171817, title = {The second-order Klein-Gordon field equation.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {2004}, year = {2004}, pages = {3775-3781}, doi = {10.1155/S0161171204406565}, zbl = {1084.81027}, language = {en}, url = {http://dml.mathdoc.fr/item/02171817} }
Gomes, D.; Capelas de Oliveira, E. The second-order Klein-Gordon field equation.. International Journal of Mathematics and Mathematical Sciences, Tome 2004 (2004) pp. 3775-3781. doi : 10.1155/S0161171204406565. http://gdmltest.u-ga.fr/item/02171817/