@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/