Ok, I'll bite. I don't have the sheet music, but a 12 bar blues is a 12 bar blues. A turnaround is a way to keep the song going, like reintroducing the tune, usually so another player can solo. Anyway, on a 12 bar blues, using this for an example, C7 C7 C7 C7 F7 F7 C7 C7 G7 F7 C7 C7, a standard turnaround would take the place of the last bar of C7. So, still a 12 bar blues. Sometimes, the last 2 bars act as a turnaround, with maybe something like a chord change every 2 beats - C7 Am7 Dm7 G7, then back to the beginning. Or, you might have: C7 Eb7 Ab7 G7. Or, C7 Eb7 Dm7 Db7, then back to the beginning. There are lots of ways to make your way back to the head (that's jazz-speak for the start ;-), or to break up the progression, keep it going, or to offer a path to more tonal variety, which you hear in lots of jazz type blues tunes. Hope this helps.