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$P(\varphi)_2$ -модели”, ТМФ, 39:3 (1979),302–306 
; I. V. Volovich, “Quasiclassical expansion of the Euclidean $P(\varphi)_2$ model”, Theoret. and Math. Phys., 39:3 (1979),477–480 
; I. V. Volovich, “Quasiclassical expansion of the Euclidean