@article{NAM_1906_4_6__135_1,
     author = {Landau},
     title = {Sur une in\'egalit\'e de {M.} {Hadamard}},
     journal = {Nouvelles annales de math\'ematiques : journal des candidats aux \'ecoles polytechnique et normale},
     pages = {135--140},
     publisher = {Carilian-Goeury et Vor Dalmont},
     volume = {4e s{\'e}rie, 6},
     year = {1906},
     language = {fr},
     url = {http://www.numdam.org/item/NAM_1906_4_6__135_1/}
}