A. Y. Kondratiev and A. L. Rebenko, “Some remarks about cluster expansion for unbounded continuous spin systems in quantum statistical mechanics”, MFAT, vol. 2, no. 2, pp. 61–69, Aug. 1996, Accessed: Feb. 04, 2026. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/13