@article{05686801,
title = {Positivity in coefficient-free rank two cluster algebras.},
journal = {The Electronic Journal of Combinatorics [electronic only]},
volume = {16},
year = {2009},
zbl = {1193.16017},
language = {en},
url = {http://dml.mathdoc.fr/item/05686801}
}
Dupont, Grégoire. Positivity in coefficient-free rank two cluster algebras.. The Electronic Journal of Combinatorics [electronic only], Tome 16 (2009) . http://gdmltest.u-ga.fr/item/05686801/