@article{1183419192, author = {Carmichael, R. D.}, title = {On Euler's $\phi$-function}, journal = {Bull. Amer. Math. Soc.}, volume = {14}, number = {3}, year = {1907}, pages = { 241-243}, language = {en}, url = {http://dml.mathdoc.fr/item/1183419192} }
Carmichael, R. D. On Euler's $\phi$-function. Bull. Amer. Math. Soc., Tome 14 (1907) no. 3, pp. 241-243. http://gdmltest.u-ga.fr/item/1183419192/