5639 Neil Hindman: The semigroup bN and its applications to number theory.
3178 Hofmann/Lawson/Pym, 347-360.

Neil Hindman: Ultrafilters and combinatorial number theory.
SLN Math. 751 (1979), 119-184.

Neil Hindman: Partitions and sums of products of integers.
Trans. AMS 247 (1979), 227-245.