As a leading authority on the Beatles, researcher and author Mark Lewisohn is well aware that there have been far too many books written about the Fab Four. "In general terms and in biographical terms, I think the Beatles have been underserved by books," he said.

Yet Lewisohn, 55, just contributed one more to the fray: the 944-page monster "Tune In: The Beatles: All These Years, Vol. 1" (Crown Archetype, $40). So what's left to say after the hundreds of books, documentaries and fictionalized biographical dramas about the Beatles? A lot, according to Lewisohn, especially when it's told accurately and with authority.

"Tune In" isn't simply another book about the Beatles — it's being received as the definitive account of the group's storied history. In Lewisohn's words, "a biographical history — not a rock biography."

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The London native spent the last 10 years researching and writing the first volume, which begins in 1845 with Liverpool during the age of John Lennon, Paul McCartney, George Harrison and Ringo Starr's grandparents and takes the reader through 1962 as the foursome is poised to release its first recordings.

Two more volumes will cover the band from 1962 on.

Given the historical magnitude of the subject to which he's devoted much of his life to, Lewisohn makes no apologies for the length of what he's written, nor the lengths he went to into researching and writing it.

"It's a story so fantastic you'd think it's all been made up," he said on a recent trip to Los Angeles from his home base near London. "But it's all true and therefore the best story of all."

Lewisohn, in fact, initially conceived of his grand-sweep exploration of the Beatles as a six-volume project — approaching Martin Gilbert's celebrated eight-volume Winston Churchill biography — but his publisher convinced him that it would be too much of an uphill battle to market.

"I call this a biographical history," said Lewisohn of the book, published Oct. 29. "It's a biography with the Beatles at the center and everything else that's happening around them. Initially, they were part of a world in which they were reacting to things around them, and when we get to volumes two and three, they're very much shaping what's going on around them."

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To capture the sense of urgency about what he's taken on, he invoked a song title, and not of one of the more than 200 songs in the Beatles' oeuvre but that of one of their biggest heroes: "It's now or never."

In previous books, Lewisohn documented the Beatles' live performances ("The Beatles Live!" 1986) and their studio activity ("The Beatles Recording Sessions: The Official Abbey Road Studio Sessions Notes, 1962-1970," 1988), for which he was granted unprecedented access to archival materials held by EMI Records and their Abbey Road studio where the Beatles made the vast majority of their records.

He also cataloged their professional and personal activities for "The Beatles Day by Day" in 1990 and synthesized what he'd gathered for those books added to it for "The Complete Beatles Chronicles" in 1992.

Along the way he's worked for EMI in producing reissues and new collections of Beatles materials and spent 15 years as a consultant on a variety of projects for McCartney.

The Beatles themselves tend not to read — or at least comment publicly on — much of what's written about them. But in his foreword to "The Complete Beatles Chronicles," Beatles producer George Martin effused: "Of all the chroniclers who have studied the lives of John, Paul, George and Ringo, Mark Lewisohn stands supreme."

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Reviews of the new book have been generally positive with near-universal praise of Lewisohn's research and most criticisms taking issue with Lewisohn's writing style.

"He's not a great stylist but he has written a game-changing study which raises the bar in a genre characterised by pap or pretension," the UK Independent's review said.

The Boston Globe's review called his prose and musical judgment "shortcomings that put a drag on this weighty account."