SEARCH Articles Figures Tables 6-Membered rings prototropic tautomerism Ring-chain tautomerism involving five-membered rings Tautomerism in Other Five-Membered Ring Lactams Tautomerism of Heterocycles: Five-Membered Rings with Tautomerism of heterocycles: five-membered rings with one Tautomerism of heterocycles: five-membered rings with two