“…For the existence, uniqueness, and regularity of the solutions of the Sobolev equation (1.1), we refer to [3,4,20]. For Sobolev equations without a convection term, many mathematicians achieve the numerical results by classical finite element methods [1,6,10,11,12] or least-squares methods [9,15,16,21,22] or mixed finite element methods [8] or discontinuous finite element methods [13,14,18,19]. But in many situations, the convection term d (x ) · ∇u exists and d (x ) is large in order to describe a convection dominated diffusion.…”