@article{SF_1995__51_1_135418,
     author = {N. Hindman and D. Strauss},
     title = {Nearly prime subsemigroups of  {{\ss}N.}},
     journal = {Semigroup forum},
     pages = {299--318},
     publisher = {mathdoc},
     volume = {51},
     number = {1},
     year = {1995},
     zbl = {0843.22005},
     url = {http://geodesic.mathdoc.fr/item/SF_1995__51_1_135418/}
}