@article{NAM_1869_2_8__42_1,
     author = {Joffroy, Joseph},
     title = {D\'emonstration de la formule $a-\sin a < \frac{a^3}{4}$},
     journal = {Nouvelles annales de math\'ematiques : journal des candidats aux \'ecoles polytechnique et normale},
     pages = {42--43},
     publisher = {Carilian-Goeury et Vor Dalmont},
     volume = {2e s{\'e}rie, 8},
     year = {1869},
     language = {fr},
     url = {http://www.numdam.org/item/NAM_1869_2_8__42_1/}
}