2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53322We review some exact solitonic solutions of string theory with higher-membrane structure. These include an axionic instanton solution of bosonic string theory as well as multi-instanton and multimonopole solutions of heterotic string theory. The heterotic solutions reveal some interesting aspects of string theory as a theory of quantum gravity.11 pagesHigh Energy Physics - Theorytext