Presumably, Peter Doggett wasn't given permission to reproduce Bowie's lyrics, with the result that, rather bizarrely, a book promising an in-depth analysis of his songs doesn't reproduce a single line. Of course, those of a certain generation will have many of those lines seared into the cerebral cortex while wearing out the vinyl. Otherwise, you'll need to print out lyric sheets if you want to follow the references! What Doggett does do, however, is provide an Ian MacDonald-style run-through of chord sequences, which will please musicologists, but leave the rest of us rather nonplussed.
His research does, however, throw up some interesting nuggets - not least the influence of Bowie's half-brother, Terry, in opening up his cultural horizons, and the fear of hereditary madness that seemed to drive him to workaholism (along with other addictions). Of course, any real attempt to track down the references in Bowie's work is a bit like lepidoptery - as soon as you pin them down and stick them behind glass, they lose the very qualities you're searching for. Bowie has been accused by Nick Kent of being a plagiarist, but his genius (not using the term lightly) lay in his capacity to soak up myriad influences and re-package them into a unique vision that managed to engage the imaginations of millions while remaining inimitable. Certainly, others have taken facets of that vision and built careers on them, but they've invariably been 2-D efforts in comparison to Bowie's widescreen 3-D.
What this book does do is remind you of the dazzlingly mercurial pace of Bowie's constant invention and reinvention - it's hard to think of another artist in any field that took so many sharp turns and vertiginous leaps as Bowie in the 70s - which is particularly staggering when you consider the volume of various substances that he took along for the ride (in addition to some pretty vexed business partnerships). It's hard to believe he got through it intact (albeit pretty physically and emotionally exhausted).
Another thing the book does is encourage you to go back to the records and marvel at the scale of inventiveness. It also reminds one of just what an amazing vocalist Bowie was - from the folk rock of the earlier work, through Space Oddity, Changes, Life on Mars, Cracked Actor, Suffragette City, Wild is the Wind, Young Americans, Heroes, the list goes on and on. It's difficult to think of anyone else that could have covered such a range.