“…, X k ⊆ Z Z * m . Comments: J. Bourgain and M. Z. Garaev [32] and M.-C. Chang and C. Z. Yao [43] have recently obtained a series of very interesting results in this direction. Comments: There are amazingly strong and general results of J. Bourgain and M.-C. Chang, see [24,25,29], which apply to very short and general sums and thus have significantly reduced the interest to this question.…”