@inproceedings{2013:invariants:formulae,
	author = "Shemyakova, E.",
	booktitle = "{Geometric Methods in Physics. XXXI Workshop, Białowieza, Poland, June 30 to July 6, 2012.}",
	editor = "{Piotr Kielanowski} and Ali, S. Twareque and Odesski, Alexander and Odzijewicz, Anatol and Schlichenmaier, Martin and Voronov, Theodore",
	note = "Accepted, http://arxiv.org/abs/1210.2938",
	series = "{Trends in Mathematics. Springer, Basel}",
	title = "{Invariants for {D}arboux transformations of Arbitrary Order for $D_x D_y +aD_x + bD_y +c$ }",
	year = "2013"
}