TY - CPAPER AU - P. D'Avanzo AU - Rosalba Perna CY - Washington, D.C. (USA) DO - 10.1063/1.2207942 PB - AIP PP - Washington, D.C. (USA) PY - 2006 TI - The frontier of darkness: the cases of GRB 040223, GRB 040422, GRB 040624 ER -