François Puitg Jean-François Dufourd Formalizing mathematics in higher-order logic: A case study in geometric modelling. 1-57 2000 234 Theor. Comput. Sci. 1-2 db/journals/tcs/tcs234.html#PuitgD00 http://dx.doi.org/10.1016/S0304-3975(98)00228-X