Tannins and related compounds CII. Sructures of terchebulin, an ellagitannin having a novel tetraphenylcarboxylic acid (terchebulic acid) moiety, and biogenetically related tannins from Terminalia chebula Retz - Lin,T.-C.; Nonaka,G.; Nishioka,I. (Chem. Pharm. Bull., 1990)