@article{10_1090_S0894_0347_98_00268_9,
     author = {Littelmann, Peter},
     title = {Contracting modules and standard monomial theory for symmetrizable {Kac-Moody} algebras},
     journal = {Journal of the American Mathematical Society},
     pages = {551--567},
     publisher = {mathdoc},
     volume = {11},
     number = {3},
     year = {1998},
     doi = {10.1090/S0894-0347-98-00268-9},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-98-00268-9/}
}