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Amy Winehouse mystery song to stay a mystery?

Amy Winehouse died at just 27 years old. Even though the Grammy winner was hailed as one of the greatest jazz singers of her generation, she succumbed to addictions that proved to be too strong, leaving millions of fans around the world morning the loss of her talent. Tuesday in the U.S., a 12-track compilation record, "Lioness: Hidden Treasures" will be released. It includes recordings of Winehouse that date back as early as 2002.

Pictures: Amy Winehouse

The compilation -- of finished and unfinished works -- was assembled by her two producers after her death.

The songs represent only some of the Winehouse material that may be released one day.

However, according to music journalist Joe Levy, one such song may never be released.

Levy said, "(There is) at least one track that one of her record company executives has said she made him promise the public will never hear. Apparently, the one recording is so deeply personal and, he says, an extremely powerful, very great song. No one will ever hear that. That is his promise to her."

Looking forward, Levy said there isn't likely enough music to fill another album. "I don't think," he said, "we have something like Jimi Hendrix or Tupac (Shakur), who left behind a lot of recordings that producers came in and cleaned up and released for years after their death."

As for the album released Monday, Levy said the material goes back to her first record.

"(Producers have) built tracks around (the vocals)," Levy said. "This is one of the rare cases where Amy Winehouse takes a back seat to the music. Very often on this record, you hear music built around vocals that she didn't intend anyone to hear."

Pictures: Amy Winehouse

The album, Levy said, isn't as strong as her "Back to Black" album, which he calls her best. "(This release) goes back to (her first record) when she really had not found her sound yet. What we get is a sunnier, happier Amy Winehouse than we have come to know. That has its sadness and its power to it. But this is a compilation, it's a hodgepodge record. I would say there are three or four truly great tracks. The rest is just interesting to hear."

The first single from the record is a cover of "Our Day will Come," by the Carpenters.

"If you listen to this record, you will hear her covering a lot of songs, and very little original songwriting on it, but a few tracks are amazingly powerful," Levy said. "A cover of 'Will You Still Love Me Tomorrow' (is) just heartbreaking. And, of course, the song with Tony Bennett, which is actually very good. Tony, at the peak of his powers now, older. Amy, just months before she died, much, much younger and sounding very much like the older, less-together voice on that recording.

"When (the song) came out, Tony Bennett lavished her with praise and called her a real jazz singer," Levy said. "You can hear on this track -- she makes very interesting melody choices, and it makes me feel (she died) much too soon. We just didn't hear all she had to give us."

Winehouse's father, Mitch Winehouse, has said, "We were stunned at how wonderful the album is. But at the moment, I can't listen to it; in the years to come, I will be able to."