. . . . . . . . . . "Pt. 19 The stories of Standard Oil, AT & T, and Microsoft demonstrates the power, importance, and problems of monopolies. Pt. 20 The rise of oligopolies and the growth of government regulations, plus a debate about airline regulation." . "Economics USA"@en . . "Oligopolies"@en . "Pt. 19 defines monopoly and explains that the degree to which a firm controls the market affects prices and economic efficiency. Pt. 20 shows how oligopolies try to avoid price competition."@en . . . . "Monopoly"@en . . . . "Economics U$A. Lesson 19, Monopoly ; Lesson 20, Oligopolies"@en . "Economics U$A. Lesson 19, Monopoly ; Lesson 20, Oligopolies" . . .