1. N. Berkovits and C. Vafa, On the uniqueness of string theory, preprint hep-th/9310170
2. J.M. Figueroa-O'Farrill, On the universal string theory, preprint hep-th/9310200
3. J.M. Figueroa-O'Farrill, Embedding the bosonic string in the NSR string, preprint, in preparation
4. H. Ishikawa and M. Kato, Note on N = 0 string as N = 1 string, preprint hep-th/9311139
5. N. Berkovits, M. Freeman and P. West, A W-string realization of the bosonic string, preprint hep-th/9312013