@article{JRAM_1990__410_153264,
     author = {J. Alexander and R. Gardner and C. Jones},
     title = {A topological invariant arising in the stability analysis of travelling waves.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {167--212},
     publisher = {mathdoc},
     volume = {410},
     year = {1990},
     zbl = {0705.35070},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1990__410_153264/}
}