stems. / R Sac Interface 7, 823-838 (2010). 28. Gai. P. & Kapadia. S. Liquidity hoarding. network externalities. and interbank market collapse.Proc.R Soc. A 466.2401-2423 (2010). 29. Schweitzer. F. et at Economic networks: the new challenges. Science 325. 422-425 (2009). 30. May,n.Levin,S.A.&Sugihar