Spatial snowdrift game of a heterogeneous agent system: cooperative behavior Ping-Ping Li, Jianhong Ke, Luo-Luo Jiang, Xian-Zhang Yuan and Zhenquan Lin Eur. Phys. J. B, 86 4 (2013) 168 Published online: 18 April 2013 DOI: 10.1140/epjb/e2013-31102-9