BRST operators for W algebras
  The study of quantum Lie algebras motivates a use of non-canonical ghosts and anti-ghosts for non-linear algebras, like W-algebras. This leads, for the W_3 and W_3^(2) algebras, to the BRST operator having the conventional cubic form. 
A.P.Isaev, S.O.Krivonos and O.V.Ogievetsky