65. “The synthesis of 7,7-difluoronorbornadiene and its quadricyclane isomer”
    Jefford, C.W.; Burger, U.; Broeckx, W.; Gehret, J.-C.E.
    Tetrahedron Lett. 1973, 14, 5187-5190.

DOI : 10.1016/S0040-4039(01)87659-0