@article{MZ_1979__167_172849,
     author = {Hans-Dieter Alber},
     title = {Estimates for the {Asymptotic} {Behavior} of {Solutions} of the {Helmholtz} {Equation,} with an {Application} to {Second} order {Elliptic} {Differential} {Operators} with {Variable} {Coefficients.}},
     journal = {Mathematische Zeitschrift},
     pages = {213--226},
     publisher = {mathdoc},
     volume = {167},
     year = {1979},
     zbl = {0407.35016},
     url = {http://geodesic.mathdoc.fr/item/MZ_1979__167_172849/}
}