1992. Sobre la necesidad de que la aceptación coincida en todo con la oferta: el espejo roto [On the necessity that the acceptance coincide entirely with the offer: The broken mirror (The "mirror-image" rule and the formation of contracts) - in Spanish], Anuario de Derecho Civil (1992) no. 3, 1011-1096 [a comparative analysis of the Counter-offer under the legal systems of Germany, England, France, United States, and under CISG Article 19]