FILE - In this Sept. 19, 2015 file photo, Adam Lambert, left, and Brian May of the Queen + Adam Lambert perform at the Rock in Rio music festival in Rio de Janeiro, Brazil. Many of the rock 'n' roll bands that were huge in 1977 will comprise a big part of the summer concert market 40 years later. Concert industry executives say nostalgia acts are still reliable sellers, with satellite and classic rock radio keeping their hits alive. (AP Photo/Felipe Dana, File) Photo: AP / Copyright 2017 The Associated Press. All rights reserved.
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