SOME PARTICULAR CASES OF THE TWO-DIMENSIONAL INTEGRODIFFERENTIAL EQUATION OF PARTICLE TRANSFER A. I. Moshinskii UDC 53.01 Some particlar cases are derived from the integrodifferential equation of particle transfer with a constant rate: they are the diffusion approximation and a differential equation of diffusion (heat conduction) of hyperbolic type with a finite velocity of propagation of perturbations. JEPTER7492019992 JEPTER749202