"Once Is Enough"

Days of Future Passed is referenced in the second verse of "Once Is Enough."  As printed in the liner notes, the lyrics are:

Sometimes you're first
Sometimes you're last
Then again you're somewhere
In your "days of future passed"

There's also a musical representation of number at the beginning of the song.  The first line is "Just ask me once," and it's sung by a single voice.  The second line is "Don't ask me twice," and it's sung by two voices.