@article{bwmeta1.element.bwnjournal-article-aav22i2p201bwm,
author = {Erd\"os, P. and Hall, R.},
title = {On the values of Euler's $\phi$-function},
journal = {Acta Arithmetica},
volume = {22},
year = {1973},
pages = {201-206},
zbl = {0252.10007},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-aav22i2p201bwm}
}
Erdös, P.; Hall, R. On the values of Euler's φ-function. Acta Arithmetica, Tome 22 (1973) pp. 201-206. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-aav22i2p201bwm/