А. С. Николаев, “Разложение Като в теории возмущений классической механики и явное выражение для генератора Депри”, ТМФ, 182:3 (2015), 465–499; A. S. Nikolaev, “Kato perturbative expansion in classical mechanics and an explicit expression for the Deprit generator”, Theoret. and Math. Phys., 182:3 (2015), 407–436
A. S. Nikolaev, “On the diagonalization of quantum Birkhoff-Gustavson normal form.”, J. Math. Phys., 37:6 (1996), 2643–2661
A. S. Nikolaev, “On operators commutative with all invariants for a harmonic oscillator with commensurable frequencies.”, J. Phys. A: Math. Gen., 28:15 (1995), 4407–4414