W. I. Skrypnik, “Kirkwood–Salsburg equation for a quantum lattice system of oscillators with many-particle interaction potentials”, Ukr. Mat. Zhurn., vol. 61, no. 5, pp. 689–700, May 2009, Accessed: Feb. 16, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3051