@article{TM_1994_203_a30,
     author = {N. Ortner and P. Wagner},
     title = {Feynman integral formulae and fundamental solutions of decomposable evolution operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {365--388},
     publisher = {mathdoc},
     volume = {203},
     year = {1994},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TM_1994_203_a30/}
}