Any cursory googling will yield several papers debunking the broken window theory for you.

Sorry, I used the term incorrectly. I'm not suggesting that graffiti increases crime, only that the presence of graffiti encourages more graffiti.

I live in Japan which is usually free of litter, put a few empty beer cans on the floor and come back 24 hours after and you will have a trash pile. I don't need a paper to tell me that.