Martin Hyland Misao Nagayama John Power Giuseppe Rosolini A Category Theoretic Formulation for Engeler-style Models of the Untyped lambda. 43-57 2006 161 Electr. Notes Theor. Comput. Sci. http://dx.doi.org/10.1016/j.entcs.2006.04.024 db/journals/entcs/entcs161.html#HylandNPR06