“…For more recent developments, see, for example, [54,37,3,15] and references therein. The papers of Babuška and Zlámal [4] and Baker [6] are the earliest contributions to the theory of discontinuous Galerkin finite element methods for fourth-order elliptic problems; for more recent results, including historical notes, see [47,34,49,50,48]. The application of discontinuous Galerkin methods to the Cahn-Hilliard equation is discussed in [20,56,58,35].…”