@article{JEMS_2014_16_1_a1,
     author = {Francisco Canto-Mart{\'\i}n and Haakan Hedenmalm and Alfonso Montes-Rodr{\'\i}guez},
     title = {Perron-Frobenius operators and the {Klein-Gordon} equation},
     journal = {Journal of the European Mathematical Society},
     pages = {31--66},
     publisher = {mathdoc},
     volume = {16},
     number = {1},
     year = {2014},
     doi = {10.4171/jems/427},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/427/}
}