Unfortunately things on the internet aren't always true. When I read your post I also did a search on the 'net and what I saw were obvious boxer/bull dog crosses. I didn't see any legitimate organizations listed.
Where I'm from the most common mix breed is a bichon/shih tzu cross. There are so many of them around that most people think they are their own breed. But they too are just mixes of 2 popular breeds.