Proposition 3.1 of our manuscript (arXiv:1410.7303) cited Theorem 1.1 of Cao-Tran announced paper in 2013 (arXiv:1311.0846). But our published paper  missed the citation  due to the corresponding author’s negligence, which we did not notice in the final proofs, and we would like to add now with this erratum. In fact, Proposition 3.1 in  is the earlier Theorem 1.1 in .
ASJC Scopus subject areas
- Applied Mathematics