@article{GDZPPN002081857,
title = {A proof of Ilieff's conjecture for polynomials with four zeros.},
journal = {Elemente der Mathematik},
volume = {43},
year = {1988},
pages = {18-21},
zbl = {0699.30006},
url = {http://dml.mathdoc.fr/item/GDZPPN002081857}
}
Cohen, G.L.; Smith, G.H. A proof of Ilieff's conjecture for polynomials with four zeros.. Elemente der Mathematik, Tome 43 (1988) pp. 18-21. http://gdmltest.u-ga.fr/item/GDZPPN002081857/