@article{ZNSL_2005_324_a11,
     author = {J. de Freitas and M. M. Popov},
     title = {Paraxial ray theory for {Maxwell's} equations},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {190--212},
     publisher = {mathdoc},
     volume = {324},
     year = {2005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2005_324_a11/}
}