1. Kane VV, Wolf AD, Jones Jr. M (1974) J. Am. Chem. Soc. 96: 2643
2. Cram DJ, Cram JM (1971) Acc. Chem. Res. 4: 204
3. For reviews; Greenberg A, Liebman JF (1978) Strained organic molecules. Academic Press, New York, p 153
4. Rosenfeld SM, Choe KA (1983) In: Keehn PM, Rosenfeld SM (eds) Cyclophanes, Academic Press, New York, vol 1, p 311
5. Bickelhaupt F, de Wolf WH (1988) Recl. Trav. Chim. Pays-Bas 107: 459