@article{JOLT_2008_18_4_a7,
     author = {Francis Valiquette},
     title = {Structure {Equations} of {Lie} {Pseudo-Groups}},
     journal = {Journal of Lie Theory},
     pages = {869--895},
     year = {2008},
     volume = {18},
     number = {4},
     url = {http://geodesic.mathdoc.fr/item/JOLT_2008_18_4_a7/}
}