Relating Linearly Superposed Periodic Solutions of Nonlinear Equations   to One Soliton Solutions
  Using new generalized Landen transformations, we prove that the solutions of the KdV and other nonlinear equations obtained recently by using a kind of superposition principle for periodic solutions are in fact novel re-expressions of well known periodic one soliton solutions. 
W. Reinhardt, A. Khare, U. Sukhatme