Linked from
The 8 pages that link to Furan, each with the reason it gives.
CoumarinCompared with: Unlike furan, coumarin has a fused benzene ring and a lactone carbonyl.
ThiopheneCompared with: Furan shares thiophene’s ring framework but contains oxygen.
FurfuralCompared with: Furan is furfural’s ring structure without its aldehyde substituent.
BenzofuranRelated: It supplies the oxygen-containing ring fused to benzene in benzofuran.