@article{10_4153_CMB_2010_062_4,
     author = {Vougalter, Vitali},
     title = {On the {Negative} {Index} {Theorem} for the {Linearized} {Non-Linear} {Schr\"odinger} {Problem}},
     journal = {Canadian mathematical bulletin},
     pages = {737--745},
     year = {2010},
     volume = {53},
     number = {4},
     doi = {10.4153/CMB-2010-062-4},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2010-062-4/}
}