Drinfeld Twists and Algebraic Bethe Ansatz of the Supersymmetric t-J   Model
  We construct the Drinfeld twists (factorizing $F$-matrices) for the supersymmetric t-J model. Working in the basis provided by the $F$-matrix (i.e. the so-called $F$-basis), we obtain completely symmetric representations of the monodromy matrix and the pseudo-particle creation operators of the model. These enable us to resolve the hierarchy of the nested Bethe vectors for the $gl(2|1)$ invariant t-J model. 
Wen-Li Yang, Yao-Zhong Zhang and Shao-You Zhao