@article{10_4064_aa100_4_1,
     author = {Kevin Ford and Richard H. Hudson},
     title = {Sign changes in $\pi _{q,a}(x)-\pi_{q,b}(x)$},
     journal = {Acta Arithmetica},
     pages = {297--314},
     publisher = {mathdoc},
     volume = {100},
     number = {4},
     year = {2001},
     doi = {10.4064/aa100-4-1},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa100-4-1/}
}