“…X uu (u, v) = (− cosh v cos u, − sinh v cos u, − cosh v sin u, − sinh v sin u), X uv (u, v) = (− sinh v cos u, − cosh v sin u, sinh v cos u, cosh v cos u), X vv (u, v) = (cosh v cos u, sinh v cos u, cosh v sin u, sinh v sin u). The surface given in Example 5.7 is a tensor product surface of E 4 , which was defined in [25] and studied in [1,2,6,4,5,26], etc. The surface is a proper pointwise slant surface with the Wirtinger function θ = |u − v| , but it is not special.…”