1. On additive properties of general sequences;Erdős;Discrete Math.,1994
2. Difference sets and inverting the difference operator;Füredi;Combinatorica,1996
3. On difference-sequences;Ruzsa;Acta Arith.,1974
4. On difference sets;Ruzsa;Stud. Sci. Math. Hungar.,1978
5. I.Z. Ruzsa, Difference sets and the Bohr topology, I, preprint.