You're welcome. A lot of these stories, especially the folk tales, don't have authors listed, because they're part of the oral tradition, and have been passed down a zillion times and the stories told in a zillion ways, no one knows who wrote them first.  If you want to see many of the sources, go to Baidu.com and search the title: 包公审石头. 

I think you might have found a typo - that's probably supposed to be 到。