Belavin A., Belavin V., Bershtein M., “Instantons and 2d superconformal field theory”, J. High Energy Phys., 2011, no. 9, 117
S. Gusein-Zade, I. Luengo, A. Melle-Hernández, “On generating series of classes of equivariant Hilbert schemes of fat points”, Mosc. Math. J., 10:3 (2010), 593–602
Szabo R.J., “Instantons, Topological Strings, and Enumerative Geometry”, Adv. Math. Phys., 2010, 107857