Доступные ссылки:

Harvard: Назаров, В. Е., Кияшко, С. Б.& Radostin, A. V. 2016. Evolution of Acoustic Waves in Homogeneous Media with Different-Modulus Nonlinearity and Relaxation. Radiophysics and Quantum Electronics, 58(10), pp. 729-737, doi: 10.1007/s11141-016-9645-2