When Donna Summer passed away at 63 on Thursday (May 17), the world was reminded -- in the most tragic way -- of the Disco Queen's legacy. As a result, her album and song sales shot up the charts. In Summer's case, her posthumous sales are even more impressive than some other artists', because her songs are only available in certain formats.

Billboard reports that nearly half of Summer's recorded material is off the market, but her current seven greatest hits compilations are making upward moves on the charts. The mag says that 2003's 'The Journey: The Very Best of Donna Summer' is likely to be the biggest mover, with all of her records collectively estimated to sell between 20 and 40,000 copies.

Summer's 1980s and 1990s recordings for Casablanca and Atlantic Records, however, are effectively off the market. Summer's estate owns the albums, which include They include 'The Wanderer' (1980), 'Donna Summer' (1982), 'Cats Without Claws' (1984), 'All Systems Go' (1987), 'I'm a Rainbow' (recorded in the 1980s but released in 1996), 'Another Place and Time' (1989) and 'Mistaken Identity' (1991). Summer's Geffen works have been off the market since 2003, while her Atlantic records were pulled in 1996 and 2009.

Summer died in Florida from lung cancer, which she suspected was caused by 9/11.

Watch the Donna Summer 'She Works Hard for the Money' Video