6-ethyl-4-methyl-2H-furo[2,3-h]chromene-2,9(8H)-dione
6-ethyl-4-methyl-2H-furo[2,3-h]chromene-2,9(8H)-dione ??
??
6-ethyl-4-methyl-2H-furo[2,3-h]chromene-2,9(8H)-dione C??? ??, ??, ??
6-ethyl-4-methyl-2H-furo[2,3-h]chromene-2,9(8H)-dione ?? ?? ? ???
???
?? ??
6-ethyl-4-methyl-2H-furo[2,3-h]chromene-2,9(8H)-dione ?? ??
???( 1)?? ??
