**TOME 41 (89), No. 1, 1998****Ion Colojoară :**Ultradifferentiable representations, p. 1-14**Janina Ewert :**The measure of nonconvexity in Fréchet spaces and a fixed point theorem for multivalued maps, p. 15-22**Ştefan Mirică :**Hamilton-Jacobi equations on possibly non-symplectic differentiable manifolds, p. 23-39**Florin Panaite :**A note on the Drinfel'd double, p. 41-44**Vasil Skënderi :**New proofs of some characterizations of the sets with the weak Radon-Nikodym property, p. 45-56**Luigia di Terlizzi and Francesca Verroca :**Contact Cauchy-Riemann Submanifolds of Locally Conformal Cosymplectic Manifolds, p. 57-69