@article{01266859, title = {The }, journal = {Bulletin of the Belgian Mathematical Society - Simon Stevin}, volume = {4}, year = {1997}, pages = {539-548}, zbl = {0929.14027}, language = {en}, url = {http://dml.mathdoc.fr/item/01266859} }
Van Steen, G. The . Bulletin of the Belgian Mathematical Society - Simon Stevin, Tome 4 (1997) pp. 539-548. http://gdmltest.u-ga.fr/item/01266859/