@article{10_4064_aa128_4_5,
     author = {Peter Borwein and Tam\'as Erd\'elyi},
     title = {Lower bounds for the number of zeros of cosine polynomials
 in the period: a problem of {Littlewood}},
     journal = {Acta Arithmetica},
     pages = {377--384},
     publisher = {mathdoc},
     volume = {128},
     number = {4},
     year = {2007},
     doi = {10.4064/aa128-4-5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa128-4-5/}
}