My neighbors use Poast Herbicide and have good luck with it. It's pricey. I once had to dig up my entire garden. I sorted each shovelful, removing all the roots. I also cleaned up rocks, pottery and broken dishes.
This was before I had a digital camera so I didn't take pictures, but I had piles of dirt. I have kept it out out by keeping an eye on the edges where it sneaks in from the grass.
