Lytvynov, E. W., Yu. G. Kondratiev, A. L. Rebenko, M. Röckner, and G. V. Schepanuk. 1997. “Euclidean Gibbs States for Quantum Continuous Systems With Boltzmann Statistics via Cluster Expansion”. Methods of Functional Analysis and Topology 3 (1): 62-81. https://zen.imath.kiev.ua/index.php/mfat/article/view/31.