@article{01139217,
title = {The symmetry of intersection numbers in group theory.},
journal = {Geometry \& Topology},
volume = {2},
year = {1998},
pages = {11-29},
doi = {10.2140/gt.1998.2.11},
zbl = {0897.20029},
language = {en},
url = {http://dml.mathdoc.fr/item/01139217}
}
Scott, Peter. The symmetry of intersection numbers in group theory.. Geometry & Topology, Tome 2 (1998) pp. 11-29. doi : 10.2140/gt.1998.2.11. http://gdmltest.u-ga.fr/item/01139217/