“…Therefore, precise mathematical analysis of mixed problems in bounded domains for dispersive equations is welcome and attracts attention of specialists in this area [2,[11][12][13][15][16][17][18] . Last years, publications on stationary and evolution dispersive equations of higher orders appeared [1,15,[19][20][21][22] . Usually, simple boundary conditions at x = 0 and x = L such as D i u(0) = D i u(L) = D l u(L) = 0, i = 0,..., l − 1 for (1) were imposed, see [1,21,22].…”