| 2930 |  | X.  ORGANO-INORGANIC COMPOUNDS, HETEROCYCLIC COMPOUNDS, NUCLEIC ACIDS AND THEIR SALTS, AND SULFONAMIDES |  |  |  |  | 
| 2932 |  | Heterocyclic compounds with oxygen hetero-atom(s) only: |  |  |  |  | 
| 2933 |  | Heterocyclic compounds with nitrogen hetero-atom(s) only: |  |  |  |  | 
| 2934 |  | Nucleic acids and their salts, whether or not chemically defined; other heterocyclic compounds: |  |  |  |  |