For the relation $Sq(U) = w.U$ I would cite Rene Thom's 1951 thesis, published as "Espaces fibres en spheres et carres de Steenrod" in Ann. Sci. Ecole Norm. Sup. (3) 69 (1952). Wu's formula $Sq(v)=w$ is not the same result.
John Rognes
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