@article{IM_1977__41_142491,
     author = {R.B. Melrose and K.G. Andersson},
     title = {The {Propagation} of {Singularities} along {Gliding} {Rays.}},
     journal = {Inventiones mathematicae},
     pages = {197--232},
     publisher = {mathdoc},
     volume = {41},
     year = {1977},
     zbl = {0373.35053},
     url = {http://geodesic.mathdoc.fr/item/IM_1977__41_142491/}
}