String spectral sequence
  We define shriek map for a finite codimensionnal embedding of fibration. We study the morphisms induced by shriek maps in the Leray-Serre spectral sequence. As a byproduct, we get two multiplicative spectral sequences of algebra wich converge to the Chas and Sullivan algebra $\mathbb{H}_*(LE)$ of the total space $E$ of a fibration. We apply this technic to find some result on the intersection morphism $I: \mathbb{H}_*(LE) \longrightarrow H_*(\Omega E)$ and to the space of free paths on a manifold $M^I$. 
Le Borgne