1. C. Adams, Largeness of the set of finite sums of sequences in N, Ph.D. dissertation, Howard University, 2006.
2. P. Balister, personal communication.
3. M. Beiglböck, V. Bergelson, T. Downarowicz and A. Fish, D-sets and the central sets theorem, Topology and its Applications 156 (2009), 2565–2571.
4. V. Bergelson, Weakly mixing PET, Ergodic Theory Dynam. Systems, 7 (1987), 337–349.
5. V. Bergelson, Ergodic Ramsey theory-an update, in Ergodic Theory of Z d -actions (M. Pollicot and K. Schmidt, eds.), London Mathematical Society Lecture Note Series 228, 1996, pp. 1–61.