@article{SIGMA_2006_2_a39,
     author = {Svetlana Kordyukova},
     title = {Nonclassical {Approximate} {Symmetries} of {Evolution} {Equations} with {a~Small} {Parameter}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2006},
     volume = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2006_2_a39/}
}