@article{article4832ffb5,
title   = {Measurement of the proton-air cross section at 's POT. 1/2' = 57 TeV with the Pierre Auger Observatory},
author = {Abreu, P. and Albuquerque, Ivone Freire da Mota e and Souza, Vitor de and Gouffon, Philippe and Carvalho, W. Rodrigues de and Peixoto, C J Todero and Tridapalli, D B},
year = {2012},
doi = {10.1103/PhysRevLett.109.062002},
journal   = {Physical Review Letters}
}