Vf. Nesterenko, CONTINUOUS APPROXIMATION FOR WAVE PERTURBATIONS IN A NONLINEAR DISCRETE MEDIUM, Combustion, explosion, and shock waves, 31(1), 1995, pp. 116-119
Wave processes in a nonlinear discrete medium are described by equatio
ns in a special form that can efficiently solve the propagation of per
turbations in very nonlinear systems, including in a ''sonic vacuum.''