Milestone Documents in African American History Book

It seems this book doesn't know what it wants to be. Light-hearted satire? Radical, subversive, serious info? It goes back and forth between being a little silly and pretty darn preachy. And then out of nowhere it talks about recording artists doing "backmasking" and I can't tell if the author really thinks The Beatles put hidden backwards messages in their music or if this is meant as humorous satire. A frustrating read, to say the least.