How have Classical Chinese negative elements (e.g. 否、無) preserved in dialects?

As part of my study of Classical Chinese, I'm looking into how the various negative elements in Classical Chinese (e.g. 不、非、否、弗、莫、未、勿、etc) have been preserved in Chinese dialects. This is not exactly an in-depth or detailed essay. I'm just looking for a brief overview, basically. Word length is 1500 words, and I'm also trying to incorporate something about how they're still used in public signs and the like, and why (which is getting posted to another topic elsewhere). This only relates to the use of negative elements, other bits are only going to be included if they're relevant. If anyone can give me any help, that would be great. It's also due Friday... (I've been slack). Suggested readings would be great too.  more