Guitart, R. (1980). Extenseurs. Diagrammes, 3. http://www.numdam.org/item/DIA_1980__3__A3_0/ 
@article{DIA_1980__3__A3_0,
  author = {Guitart, Ren\'e},
  title = {Extenseurs},
  journal = {Diagrammes},
  note = {talk:3},
  publisher = {Universit\'e Paris 7, Unit\'e d'enseignement et de recherche de math\'ematiques},
  volume = {3},
  year = {1980},
  zbl = {0509.18009},
  mrnumber = {684911},
  language = {fr},
  url = {http://www.numdam.org/item/DIA_1980__3__A3_0/}
}