(CNN) -- The music isn't new, but the discovery that a young Wolfgang Amadeus Mozart "almost certainly" composed it is a stunning revelation.
A researcher in Austria says the works were probably transcribed by Mozart's father, as young Mozart played.
The two compositions -- a concerto in G and a prelude in G -- have long been in the files at the International Mozarteum Foundation in Salzburg, Austria, as anonymous works and were even published in the book "New Mozart Edition" in 1982.
Now Ulrich Leisinger, director of the foundation's research department, believes the works actually were composed by Mozart before he was old enough to write music, and that Mozart's father, Leopold, transcribed them.
The foundation said in a statement that Leisinger analyzed the handwriting and other "stylistic criteria" to determine the music was "almost certainly unknown compositions by" the young Mozart.
The compositions were found in a book, compiled by Mozart's father, that was used for practice and the musical education of both Mozart and his sister, according to the statement.
Leisinger's analyses "support the claim that they were actually composed by the young Mozart, who was not yet versed in musical notation, and transcribed by his father as the boy played the works at the keyboard," the statement said.
Jeffrey Kimpton, president of the Interlochen Center for the Arts in Michigan, called the works "a remarkable historical find."
He said Leopold Mozart transcribed his son's early works as a way of preserving them.
"When parents go to a piano recital of an early student, a young student, who's playing for the first time, they get a video tape, they get a DVD, that's a way of recording it," Kimpton said. "I think what's exciting is that Mozart's father wanted to preserve this incredible genius. The young boy at this time didn't know how to write music, but he sure could play it. It's like a family photo or video album."
Finding such historical treasures is like detective work, Kimpton said.
"You're kind of putting together a DNA picture," he said. "This particular museum has hundreds of manuscripts. Over time as you learn more and more by various scholars working on this, you might turn the page and you may have looked at it a hundred times before but suddenly begin to see some things or understand some things that make some sense."
Mozart was born in Salzburg in 1756 and started composing when he was 5 years old. By the time of his death in 1791, he had written more than 600 pieces of music.