%0 Journal Article
%A Arthur W. Apter
%T Indestructibility, strongness, and 
 level by level equivalence
%J Fundamenta Mathematicae
%D 2003
%P 45-54
%V 177
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4064/fm177-1-3/
%R 10.4064/fm177-1-3
%G en
%F 10_4064_fm177_1_3