Since 1988, two authoritative sources have attempted to clarify or revise Weininger's original description of SMILES. A 2003 book chapter by Weininger addressed some of the limitations of the paper . The Daylight Theory Manual, a website maintained by SMILES's corporate sponsor, Daylight Chemical Information Systems, Inc. ("Daylight"), recapitulates published material . The lack of other authoritative sources describing SMILES is consistent with Weininger's reported disinterest in traditional scientific publication .