Here is Nishiura and Waterman's paper.
> _Nishiura, T.; Waterman, D._ , **Reflexivity and summability**, Stud. Math. 23, 53-57 (1963). ZBL0121.09402.
Albert Baernstein gives a counter-example for the converse in the paper:
> _Baernstein, Albert II_ , **On reflexivity and summability**, Stud. Math. 42, 91-94 (1972). ZBL0228.46014.