Noohi, Behrang Max Planck Institute for Mathematics, Max Planck Society;
https://smf.emath.fr/publications/topologie-des-cordes-des-champs-differentiels (Publisher version)
arXiv:0712.3857.pdf (Preprint), 2MB
Behrend, K., Ginot, G., Noohi, B., & Xu, P. (2012). String topology for stacks. Paris: Société Mathématique de France.