Charm in cosmic rays (The long-flying component of EAS cores)
  Experimental data on cosmic ray cascades with enlarged attenuation lengths (Tien-Shan effect) are presented and analyzed in terms of charm hadroproduction. The very first estimates of charm hadroproduction cross sections from experimental data at high energies are confirmed and compared with recent accelerator results. 
I.M. Dremin, V.I. Yakovlev