Schrödinger operators with almost periodic potentials in nonseparable Hilbert spaces Jan Herczyński — 1987 Banach Center Publications
Semiclassical limit for perturbations of non-resonant rotators Jan Herczyński — 1990 Annales de l'I.H.P. Physique théorique
Perturbation properties of the spectrum of periodic Schrödinger operators Marek Burnat; Jan Herczyński; Bogdan Zawisza — 1987 Banach Center Publications