There is no books that I can find that explain this, and all I've gathered from the internet is that "Crosby was largely responsible for the innovative combination of fourth and fifth high harmony parts." But what gets me, is that the basics of vocal harmony tell you to avoid 4th/5th harmonies and that they give you a gregorian chant effect. But then why does it sound so good on byrds recordings, if this is true?
Maybe I'm missing something and have no idea what I'm talking about, but thats why I'm posting this
