@article{04192529, title = {Exterior parallelism for polyhedra.}, journal = {Mathematica Pannonica}, volume = {2}, year = {1991}, pages = {95-106}, zbl = {0723.51007}, language = {en}, url = {http://dml.mathdoc.fr/item/04192529} }
Wegner, Bernd. Exterior parallelism for polyhedra.. Mathematica Pannonica, Tome 2 (1991) pp. 95-106. http://gdmltest.u-ga.fr/item/04192529/