Heterocyclic Compounds, 4 or More Rings. Five Ring Heterocyclic Compounds . Four Ring Heterocyclic Compounds . Fused Heterocyclic Compounds, Five-Ring . Fused Heterocyclic Compounds, Four-Ring . Heterocyclic Compounds with Four or More Rings . Heterocyclic Compounds, 4-Ring . Heterocyclic Compounds, 5-Ring . Heterocyclic Cpds, 4 Ring . Heterocyclic Cpds, 4 or More Rings . Heterocyclic Cpds, 5 Ring . 4-Ring Heterocyclic Compounds . 5-Ring Heterocyclic Compounds . Fused Heterocyclic Compounds, Five Ring . Fused Heterocyclic Compounds, Four Ring . Heterocyclic Compounds, 4 Ring . Heterocyclic Compounds, 5 Ring . Heterocyclic Compounds with 4 or More Rings . 1.00