Доступные ссылки:

Harvard: Abrashkin, A. A.& Пелиновский, Е. Н. 2017. Lagrange form of the nonlinear Schrödinger equation for low-vorticity waves in deep water. Nonlinear Processes in Geophysics, 24(2), С. 255-264, doi: 10.5194/npg-24-255-2017