Reflection K-Matrices of the 19-Vertex Model and XXZ Spin-1 Chain with   General Boundary Terms
  We derive and classify all solutions of the boundary Yang-Baxter equation (or the reflection equation) for the 19-vertex model associated with $U_q(\widehat{sl_2})$. Integrable $XXZ$ spin-1 chain hamiltonian with general boundary interactions is also obtained. 
Takeo Inami, Satoru Odake and Yao-Zhong Zhang