Synthesis and Molecular Structure of 1α-Hydroxy-13-Isopropyl-7,10A-Dimethyl-4-Oxooctadecahydro-4B,12-Methanochryseno[1,12-BC]Furan-7-Carboxylic Acid and Methyl 1β-Acetoxy-13-Acetyl-7,10A-Dimethyl-4-Oxohexadecahydro-1H-4B,12-Ethenochrysene-7-Carboxylate - Tret'yakova, E. V.; Rybalova, T. V.; Polovyanenko, D. N. (Journal of Structural Chemistry, 2023)