For Yorkies I aways recommend the YTCA website:
Breeder Listing For the Biewer, I recommend you talking with For Biewers I recommend you talking to someone who's a member of the BBCA
Biewer Breed Club of America. Both of these types of breeders are expensive, but I'd rather you save up and buy a healthy dog then try and buy a bargain dog who could end up costing you more in the long run.