@article{IM_1980__56_142686,
     author = {V.G. Kac},
     title = {Infinite {Root} {Systems,} {Representations} of {Graphs} and {Invariant} {Theory.}},
     journal = {Inventiones mathematicae},
     pages = {57--92},
     publisher = {mathdoc},
     volume = {56},
     year = {1980},
     zbl = {0427.17001},
     url = {http://geodesic.mathdoc.fr/item/IM_1980__56_142686/}
}