The Wald Memorial Lectures delivered in Seattle in August 1977, and summarised here, ranged over a variety of applications in both pure and applied probability of the idea of exchangeability, and particularly of de Finetti's theorem. Particular emphasis was placed on two contrasting themes, some recent work of Aldous on the subsequence principle, and consequences of de Finetti's theorem for certain problems in population genetics.
"Uses of Exchangeability." Ann. Probab. 6 (2) 183 - 197, April, 1978. https://doi.org/10.1214/aop/1176995566