Progress of Theoretical PhysicsDefinition of Normal Product and Wick's Theorem in Statistical MechanicsMasanao KitamuraPublished Jun 1, 1964• 0 citationsPublisherAbstractMasanao Kitamura; Definition of Normal Product and Wick’s Theorem in Statistical Mechanics*), Progress of Theoretical Physics, Volume 31, Issue 6, 1 June 1964,DOI10.1143/ptp.31.1160