Here are the standards and the parent club. There are many promoted as such that aren't so if you are looking for a real one make sure you get AKC or UKC registration applications (many are dual as standards for show don't vary much). Best place to start looking is at the breed club usually.
www.ukcdogs.com www.amstaff.org www.akc.org
www.ukcdogs.com www.amstaff.org www.akc.org