Letter: Labetalol and clonidine in severe hypertension.
D000959:Antihypertensive Agents / Q000627:therapeutic use*; D003000:Clonidine / Q000627:therapeutic use*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*
D000959:Antihypertensive Agents; D003000:Clonidine