“…In applied sciences, many model problems take the formulation of fourth order elliptic perturbation problems, such as, e.g., the linearized Cahn-Hilliard equation [9,31,39,43,[51][52][53], and the strain gradient problem [1,10,11,28,33,49]. In order for the robust discretisation of such problems, numerical schemes that work for both fourth and second order problems are needed.…”