@article{05188492, title = {The fundamental group and Galois coverings of hexagonal systems in 3-space.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {2006}, year = {2006}, doi = {10.1155/IJMMS/2006/47381}, zbl = {1146.05045}, language = {en}, url = {http://dml.mathdoc.fr/item/05188492} }
De La Peña, J.A.; Mendoza, L. The fundamental group and Galois coverings of hexagonal systems in 3-space.. International Journal of Mathematics and Mathematical Sciences, Tome 2006 (2006) . doi : 10.1155/IJMMS/2006/47381. http://gdmltest.u-ga.fr/item/05188492/