@article{alr09,
author = "C. Andr{\'e}s and L. Llana and I. Rodr{\'\i}guez",
title = "Formally transforming user-model testing problems into implementer-model testing problems and viceversa",
journal="Journal of Logic and Algebraic Programming",
volume ="78",
number ="6",
pages = "425--453",
year = "2009"}