XI: 17, 324-326, LNM 581 (1977) BERNARD, Alain Complément à l'exposé précédent (Martingale theory) This paper is a sequel to 1116, which it completes in two ways: it makes it independent of a previous proof of the Fefferman inequality, which is now proved directly, and it exhibits atoms of the first kind appropriate to the quadratic norm of $H^1$ Keywords: Atomic decompositions, $H^1$ space, $BMO$ Nature: Original Retrieve article from Numdam