@article{SIGMA_2008_4_a7,
     author = {E. G. Kalnins and Willard Miller. Jr. and Sarah Post},
     title = {Models for {Quadratic} {Algebras} {Associated} with {Second} {Order} {Superintegrable} {Systems} in {2D}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2008},
     volume = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2008_4_a7/}
}