N. N. Rozhenko, “Quantum oscillator in an infinite-particle harmonic system”, Ukr. Mat. Zhurn., vol. 45, no. 9, pp. 1266–1273, Sep. 1993, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5929