@incollection{SB_1976-1977__19__167_0,
     author = {Hirsch, Francis},
     title = {Op\'erateurs carr\'e du champ},
     booktitle = {S\'eminaire Bourbaki : vol. 1976/77, expos\'es 489-506},
     series = {S\'eminaire Bourbaki},
     note = {talk:501},
     pages = {167--182},
     publisher = {Springer-Verlag},
     number = {19},
     year = {1978},
     mrnumber = {521767},
     zbl = {0389.31005},
     language = {fr},
     url = {http://archive.numdam.org/item/SB_1976-1977__19__167_0/}
}