“…Various different difference schemes have been constructed which are uniformly convergent on equidistant meshes as well as schemes on specially constructed, mostly Shishkin and Bakvhvalov-type meshes, where ϵ-uniform convergence of second order has been demonstrated, see e.g. [11,13,14,24,26,28,29], as well as schemes with ϵ-uniform convergence of order greater than two, see e.g. [7,8,9,32,33].…”