.Gamma.-Oxo-2-dibenzofuranbutyric acid 2-Dibenzofuranbutanoic acid, .gamma.-oxo- 38873-55-1 4-Dibenzo[b,d]furan-2-yl-4-oxobutanoic acid AIDS-125915 AIDS125915 AY 21367 AY-21,367 Furobufen NSC89140