A plane wave of frequency \(\omega\) propagates so that a certain phase of oscillation moves along the \(x, y, z\) axes with velocities \(v_{1}\), \(v_{2}, v_{3}\) respectively. Find the wave vector \(\mathbf{k}\), assuming the unit vectors \(\mathrm{e}_ {x}, \mathrm{e}_ {y}, \mathrm{e}_ {z}\) of the coordinate axes to be assigned.