On irreducibility of the principal series -- La Formule de Plancherel Pour un Groupe de Lie Resoluble Connexe -- On finite generation of invariants for certain sub-algebras of a semi-simple lie algebra -- Generic representations -- A characteristic variety for the primitive spectrum of a semisimple lie algebra -- Remarque sur la Covariance de Certains Operateurs Differentiels -- Classification theorems for representations of semisimple lie groups -- Integrales d'Entrelacement sur des Groupes de Lie Nilpotents et Indices de Maslov -- Decomposition Spectrale des Reprรฉsentations Lisses -- Two character identities for semisimple lie groups -- Spherical functions in spin0(1,d)/Spin(d?1) for d=2,4 and 8