A Comment on the Letter by Manuel Arrayás, Marco A. Fontelos, and José L. Trueba, Phys. Rev. Lett. 95, 165001 (2005). The authors of the Letter offer a Reply.
American Physical Society
doi.org/10.1103/PhysRevLett.101.139501
Physical Review Letters
Multiscale Dynamics

Ebert, U., & Derks, G. (2008). Comment on 'Mechanism of Branching in Negative Ionization Fronts'. Physical Review Letters, 101, 1–1. doi:10.1103/PhysRevLett.101.139501