Lant Pritchett explains this notion in details in his book: Let Their People Come: Breaking the Policy Deadlock on International Labor Mobility.
Lant Pritchett anafafanua dhana hii kwa kina katika kitabu chake: Waache Watu Wake Waje; Kuvunjwa kwa Ukomo wa Sera ya Uhamiaji wa Kimataifa wa Nguvukazi.