@article{02104399,
title = {Commutators and squares in free groups.},
journal = {Geometry \& Topology},
volume = {8},
year = {2004},
pages = {595-602},
doi = {10.2140/agt.2004.4.595},
zbl = {1055.20025},
language = {en},
url = {http://dml.mathdoc.fr/item/02104399}
}
Sarkar, Sucharit. Commutators and squares in free groups.. Geometry & Topology, Tome 8 (2004) pp. 595-602. doi : 10.2140/agt.2004.4.595. http://gdmltest.u-ga.fr/item/02104399/