%0 Journal Article
%A Jörgen Backelin
%T On the number of semigroups of natural numbers.
%J Mathematica Scandinavica
%D 1990
%P 197-215
%V 66
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MS2_1990__66_1_167105/
%F MS2_1990__66_1_167105