BFT embedding of the Green-Schwarz superstring and the pure spinor   formalism
  We worked out the Batalin-Fradkin-Tyutin (BFT) conversion program of second class constraints to first class constraints in the GS superstring using light cone coordinates. By applying this systematic procedure we were able to obtain a gauge system that is equivalent to the recent model proposed by Berkovits and Marchioro to relate the GS superstring to the pure spinor formalism. 
Alejandro Gaona and J. Antonio Garcia