If you can't find any referrals here, use Google to find breeders then don't be afraid to contact others for referrals. If they have a Tonkingese breed club, start there. Get referrals from the breeders, but also ask other breeders about each other.
If their club is anything like most dog clubs, we can't say anything bad about a breeder who is also in the club. So sometimes the less said means a lot.