SALMANPOUR, S. et al. 2010. Silica Gel Powder Catalyzed Stereoselective Synthesis of Dialkyl 1,1-Diacetyl-8a-hydroy-8-oxo-1,2,8,8atetrahydrocyclopenta[ a]indene-2,3-dicarboxylates from the Reaction of Dialkyl 2-(1-Acetyl-2-oxopropyl)-3-(tributylphosphoranylidene). Asian Journal of Chemistry. 19, 2 (Mar. 2010), 1567–1569.