Subramanian, Arvind Optimal tariffs : theory and practice / Arvind Subramanian, Ali Ibrahim & Luis A. Torres-Castro - Washington : International Monetary Fund (IMF) , 1993 - 56p. : ill. ; 30 cm. - IMF Working paper 93-50 . Includes bibliographical references. Subjects--Topical Terms: Tariffs Gov. Doc. Class. No.: UN IMF WP-93-50