TY - JOUR AU - D. Lazzati AU - Mitchell Begelman BT - The Astrophysical Journal DA - 04/2006 DO - 10.1086/500502 PY - 2006 SP - 972 EP - 977 T2 - The Astrophysical Journal TI - Thick Fireballs and the Steep Decay in the Early X-Ray Afterglow of Gamma-Ray Bursts VL - 641 SN - 0004-637X ER -