@article{PDML_1987___1B_175_0,
     author = {Helmstetter, Jacques},
     title = {D\'eformations d'alg\`ebres sym\'etriques conservant le coproduit ou le produit int\'erieur},
     journal = {Publications du D\'epartement de math\'ematiques (Lyon)},
     pages = {175--185},
     publisher = {Universit\'e Claude Bernard - Lyon 1},
     number = {1B},
     year = {1987},
     mrnumber = {907073},
     language = {fr},
     url = {http://archive.numdam.org/item/PDML_1987___1B_175_0/}
}