Peters, K., Peters, E.-M., Sammtleben, F., & Christl, M. (2000). Crystal structure of (1β,4α,4aβ,5α,8α,8aβ)-octahydro-3-oxo-4-syn-9-diphenyl-1,4-ethano-5,8-methano-2-benzopyran-1-carboxylic acid methyl ester, (C7H10)[C5H3O2(C6H5)2(COOCH3)]. Zeitschrift für Kristallographie: New Crystal Structures, 215, 49-50.