© 2018 Elsevier B.V. After manuscript [3] appeared online, previously published work that exhibits similar concepts was brought to the attention of the authors and the Editor-In-Chief. In particular, we mention the IGFEM [1] which introduced the concept of associating enriched degrees of freedom with element edges, and the subsequent DE-FEM [2] that employed both strong and weak discontinuous enrichment functions. The authors regret not having identified these manuscripts prior to publication and citing them in the introduction to manuscript [3].