At times, steps in the cascade involved one researcher's reading the works of previous researchers, as when Treynor read Modigliani and Miller. At other times, especially in the early stages of the cascade, extensive personal contact was involved, as in the cases of Sharpe's relation to Markowitz, Black's relation to Treynor, Merton's relation to Black and Scholes, and Emanuel Derman's relation to Black.

Donald MacKenzie, An Engine, Not a Camera, loc. 1092