[bchgirl]

To clear up any further misunderstandings...here is the complete quotation of the question and answer provided by Gertrude Biewer. Italics mine.

14. Did you and your husband ever go back to breed Yorkshire after getting enough genetic material to continue breeding Biewers? Did you stand for a pure breeding, or did you think a Yorkshire should be mixed in every now and then?
It’s a shame that people mix Yorkshires in. It is a fraud towards owner and other breeders.

The translation and letter are easily found on line. I was reluctant to link a website without an owner's permission, but google can provide a source easily.

One needn't leave YT to find proof of biewer x parti breedings.