@article{10_4007_annals_2005_162_1377,
     author = {Antonio C\'ordoba and Diego C\'ordoba and Marco A. Fontelos},
     title = {Formation of singularities for a transport equation with nonlocal velocity},
     journal = {Annals of mathematics},
     pages = {1377--1389},
     publisher = {mathdoc},
     volume = {162},
     number = {3},
     year = {2005},
     doi = {10.4007/annals.2005.162.1377},
     mrnumber = {2179734},
     zbl = {1101.35052},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4007/annals.2005.162.1377/}
}