Bases normales autoduales et groupes unitaires en caract\'eristique 2
  Let k be a field of characteristic 2 and let L/k be a finite Galois extension with Galois group G. We show the equivalence of the following two properties:   (*) The group G is generated by elements of order 2 and by elements of odd order.   (**) There exists an element x of L such that Tr(x) = 1 and T(x.g(x)) = 0 for every non trivial element g of G. 
Jean-Pierre Serre
math.AG