I mentioned in another thread about a book I'm reading called Classic Rock Stories by Tim Morse.
On page 41, RE: Black Dog, Jimmy Page says: "I suggested how you get the breaks with the vocals. That's it, I've finally owned up, as no one else will in the band, but that was the idea to give it the vocal thing, then the riffs come in. I guess if you want to say that we leaned on something so far as the structure of it, you remember 'Oh Well' by Fleetwood Mac, where it stops and there's a vocal, so there you are...now they'll sue us!"
Pg 43, Gold Dust Woman, Mick Fleetwood says: "Stevie (Nicks) did her first vocal track of 'Gold Dust Woman' in a fully lit studio. The song needed both a mysterious power and a lot of emotionality. As take followed take, Stevie began to withdraw into herself, reaching inside for the magic. The lights were dimmed, a chair was brought in so she could sit, saving her strength at three in the morning, and she wrapped herself in a big cardigan sweater to ward off the predawn chill. An hour later she was almost invisible in the shadows, elfin under big headphones, hunched over in her chair, alternately choosing from her supply of tissues, a Vick's inhaler, a box of lozenges for her sore throat, and a bottle of mineral water. Gradually she gained total command of her song. On the eighth take, exhausted but exalted, she sang the lyrics straight through to perfection."