@article{05256873,
title = {The Euler characteristic of a category.},
journal = {Documenta Mathematica},
volume = {13},
year = {2008},
pages = {21-49},
zbl = {1139.18009},
language = {en},
url = {http://dml.mathdoc.fr/item/05256873}
}
Leinster, Tom. The Euler characteristic of a category.. Documenta Mathematica, Tome 13 (2008) pp. 21-49. http://gdmltest.u-ga.fr/item/05256873/