List of citations in Numdam for : Characteristic initial value problem for hyperbolic systems of second order differential equations

Annales de l'I.H.P. Physique théorique, Volume 53 (1990) no. 2, pp. 159-216.

Séminaire Bourbaki volume 2011/2012 exposés 1043-1058, Astérisque, no. 352 (2013), Talk no. 1051, 71 p.

Annales de la Faculté des sciences de Toulouse : Mathématiques, Serie 6, Volume 11 (2002) no. 3, pp. 351-376.