1. in : Non-Benzenoid Aromatic Compounds. Interscience, New York 1959, S. 171.
2. HEPTALENE
3. in : Non-Benzenoid Aromatic Compounds. Interscience, New York 1959, S. 141
4. : Carbocyclic Non-Benzenoid Aromatic Compounds. Elsevier, Amsterdam 1966, S. 205;
5. : Aromaticity. McGraw Hill, London 1972, S. 146.