Peter Møller Neergaard Morten Heine Sørensen Conservation and Uniform Normalization in Lambda Calculi with Erasing Reductions. 149-179 2002 178 Inf. Comput. 1 http://dx.doi.org/10.1006/inco.2002.3153 db/journals/iandc/iandc178.html#NeergaardS02