Think of the entire 33 1/3 series of books as little psychological profiles of some of history's most profoundly significant records. These are deep studies where lyrics are carefully scrutinized and harmonic content is deconstructed and reconfigured in thoughtful and meaningful ways.
The authors here are, variously, broadcasters and film critics, editors of stylish and highbrow magazines, and even university-level music professors.
You're not going to be reading surface evaluations or simple analyses. On the downside, though, some of these interpretations do tend to fall somewhere in the "How did they ever come up with this notion?" pile.
In Aqualung, author Allan F. Moore, Professor of Popular Music and Head of the Department of Music and Sound Recording at the University of Surrey, claims:
"In the early rise of heavy rock (Groundhogs, Hendrix, Grand Funk Railroad, King Crimson, Black Sabbath), the non-ironic use of orchestral instruments was anathema, representing the importation of 'their' agenda into 'our' music."Yes, the quote is taken out of context, but the main offense here is grouping Crimson with the Groundhogs as "heavy rock." That is wrong. But that is not the salient point being made here; Moore is discussing the use of strings/classical elements in electric music.
These are fun books for that very reason - they dig deeper than just about anything else written about these particular records.
If you're truly seeking to unravel the more obscure elements of these albums, then you need to check out the 33 1/3 series of books.