X-1991-09: Beklemishev, L.D. (1991) On Bimodal Provability Logics for P1-axiomatized Extensions of Arithmetical Theories. [Report]
X-1990-03: Beklemishev, L.D. (1990) On the Complexity of Arithmetical Interpretations of Modal Formulae. [Report]
X-1990-08: Beklemishev, L.D. (1990) Provability Logics for Natural Turing Progressions of Arithmetical Theories. [Report]