@article{10_4064_sm154_3_1,
     author = {Rinka Azuma},
     title = {Approximation theorem for evolution operators},
     journal = {Studia Mathematica},
     pages = {195--206},
     year = {2003},
     volume = {154},
     number = {3},
     doi = {10.4064/sm154-3-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm154-3-1/}
}