Citation: Ah. Schmidt et al., OXOCARBONS AND RELATED-COMPOUNDS .21. DIE LS-ALDER REACTIONS OF 3-HALOGENO-3-CYCLOBUTENE-1,2-DIONES WITH 1,1'-BI-1-CYCLOALKENYLS - SYNTHESIS OF DICYCLOALKANO-ANNULATED DIHYDROBENZOCYCLOBUTENEDIONES AND BENZOCYCLOBUTENEDIONES, Synthesis, (4), 1994, pp. 422-426