@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/