PetrinaE. D., and PetrinaD. Ya. “Existence of Equilibrium States of Systems of Hard Spheres in the Boltzmann-Enskog Limit Within the Frame Work of the Grand Canonical Ensemble”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 1 (January 25, 1997): 112–121. Accessed November 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4990.