%0 Serial %A Ko Eunkyung %D 2011 %G No linguistic content %B Electronic journal of qualitative theory of differential equations %@ 1417-3875 %T On S-shaped and reversed S-shaped bifurcation curves for singular problems %U http://acta.bibl.u-szeged.hu/42333/1/ejqtde_2011_031_001-012.pdf