Nonlinear Realizations of the $W_3^{(2)}$ Algebra
  In this letter we consider the nonlinear realizations of the classical Polyakov's algebra $W_3^{(2)}$. The coset space method and the covariant reduction procedure allow us to deduce the Boussinesq equation with interchanged space and evolution coordinates. By adding one more space coordinate and introducing two copies of the $W_3^{(2)}$ algebra, the same method yields the $sl(3,R)$ Toda lattice equations. 
S. Bellucci, V. Gribanov, S. Krivonos and A. Pashnev