Drinfel'd Doubles and Lusztig's Symmetries of Two-Parameter Quantum   Groups
  We find the defining structures of two-parameter quantum groups $U_{r,s}(\frak g)$ corresponding to the orthogonal and the symplectic Lie algebras, which are realized as Drinfel'd doubles. We further investigate the environment conditions upon which the Lusztig's symmetries exist between $(U_{r,s}(\frak g), < ,>)$ and its associated object $(U_{s^{-1}, r^{-1}}(\frak g), < | >)$. 
Nantel Bergeron, Yun Gao and Naihong Hu