@article{JLT_2006_16_4_JLT_2006_16_4_a3,
     author = {X.-P. Xu },
     title = {Tree {Diagram} {Lie} {Algebras} of {Differential} {Operators} and {Evolution} {Partial} {Differential} {Equations}},
     journal = {Journal of Lie theory},
     pages = {691--618},
     publisher = {mathdoc},
     volume = {16},
     number = {4},
     year = {2006},
     url = {http://geodesic.mathdoc.fr/item/JLT_2006_16_4_JLT_2006_16_4_a3/}
}