Normalizing extensions I.- Normalizing extensions II.- Commutant des Modules de Longueur Finie sur Certaines Algèbres Filtrées.- Maximal orders applied to enveloping algebras.- Fxtensions of valuations on skew fields.- Extensions of simple by simple unit-regular rings.- Invertible 2×2 matrices over skew polynomial rings.- Hereditary P. I. algebras.- Grade et Théorème d’intersection en algèbre Non commutative.- Théorème de Hopkins pour les Catégories de Grothendieck.- The moore-penrose inverse for matrices over skew polynomial rings.- The lattice type of orders: A diagrammatic approach. I.- Arithmetically graded rings .I..- Radicals and chain conditions.- Graded azumaya algebras and brauer groups.- Birationality of P.I. rings and non-commutative varieties.- Skew power series rings and some homological properties of filtered rings.