Anytime I see a topic like this I always respond the same way: Listen closely to the song and figure out the words you can, then make up the rest. You don't need "definitive lyrics." This is rock'n'roll, it shouldn't be paint-by-numbers/follow the instructions to a "T." No one's going to care if you mess up a word here or a line there. In fact, I bet no one would even notice! Besides, I think it's better if you do! Makes the cover more your own.