An upper limit to the proton fraction in cosmic rays above 10.sup.19./sup. eV from the Pierre Auger Observatory

Abraham, J., Aglietta, M., Aguirre, C., Boháčová, M., Hrabovský, M., Mandát, D., Nosek, D., Nožka, L., Palatka, M., Pech, M., Prouza, M., Řídký, J., Schovánek, P., Šmída, R., Trávníček, P. An upper limit to the proton fraction in cosmic rays above 10¹⁹ eV from the Pierre Auger Observatory. Astroparticle Physics. 2007, 27(-), 155-168. ISSN 0927-6505. E-ISSN 1873-2852.