@article{IM2_1992_38_3_a6,
     author = {A. A. Tuzhilin},
     title = {Morse-type indices of of two-dimensional minimal surfaces in $\mathbf R^3$ and $\mathbf H^3$},
     journal = {Izvestiya. Mathematics },
     pages = {575--598},
     publisher = {mathdoc},
     volume = {38},
     number = {3},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1992_38_3_a6/}
}