Hirota's Solitons in the Affine and the Conformal Affine Toda Models
  We use Hirota's method formulated as a recursive scheme to construct complete set of soliton solutions for the affine Toda field theory based on an arbitrary Lie algebra. Our solutions include a new class of solitons connected with two different type of degeneracies encountered in the Hirota's perturbation approach. We also derive an universal mass formula for all Hirota's solutions to the Affine Toda model valid for all underlying Lie groups. Embedding of the Affine Toda model in the Conformal Affine Toda model plays a crucial role in this analysis. 
H.Aratyn, C.P. Constantinidis, L.A. Ferreira, J.F. Gomes and A.H.   Zimerman