“…This work also provides bilinear versions of the linear results in [18,50,22,20,35]; in particular there is a close parallel with the Hardy space results in [35]. There has also been a considerable development of bilinear Littlewood-Paley-Stein theory in recent years, see for example [42,43,32,29,25,5,24]. All of these articles deal with Littlewood-Paley-Stein operator mapping properties from L p 1 × L p 2 into L p for p 1 , p 2 > 1.…”