%0 Journal Article
%A S. Lajos
%T On existence of the identity element in a semigroup
%J Matematički vesnik
%D 1965
%P 155 
%V 17
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MV_1965_17_2_a9/
%F MV_1965_17_2_a9