@article{article0caff3c0,
title   = {Extremal problems on sun-free sets and coverings in tridimensional spaces},
author = {Monte Carmelo, Emerson L. and Mendonça Neto, Candido Ferreira Xavier},
year = {2009},
doi = {10.1007/s00010-009-2971-0},
journal   = {Aequationes Mathematicae}
}