5[4]Holmstrom B,P Milgrom.Aggregation and Linearity in the Provision of Intertemporal Incentives[J].Econometrica,1987,(55):303-328.
6[5]Holmstrom B,P Milgrom.Multi-Task Principal-Agent Analyses:Incentive Contracts Asset Ownership and Job design[J].Journal of Law,Economics and Organizaton,1991,(7):24-52.