. . . . "Indexes"@en . . . . "Product differentiation, search costs, and competition in the mutual fund industry : a case study of S & P 500 index funds"@en . . . "Product Differentiation, Search Costs, and Competition in the Mutual Fund Industry a Case Study of the S & P 500 Index Funds"@en . . . . "Product differentiation, search costs, and competition in the mutual fund industry a case study of S & P 500 index funds"@en . . . . . . . . "Product differentiation, search costs, and competition in the mutual fund industry: a case study of S & P 500 index funds" . . .