Please take a moment to read this sticky thread: How to spot a reputable breeder
In Summerrain's first post she has given the link to the SKG, the Swiss Kennel Club. Further, Jack Russels are governed under the Terrier Club and the Russell Terrier CLub: http://www.terrierclub.ch/ http://www.russellterrierclub.ch/zuechter.html
Be aware that most good breeders will have waiting lists.
And just because rescue is my thing
I'll take the opportunity to point out that there are several jack russels currently in need of homes: (Croquette, Stella, Rambo and Mila (Mila may be a JR mix). Sadly, JRs come into rescue frequently. http://www.tierdatenbank.ch/cms/tier...unschtier.html
And because I'm a stickler for Da Roolz... if this is the first time you have owned a dog in Switzerland*, you will need to take the SKN theory course BEFORE you get your dog - so best do that now. Regardless of experience will have to take the SKN Practical with your new canine friend within the first year of ownership.
*(An exception: if an experienced dog owner outside Switzerland you'd need to present evidence to apply for dispensation from the theory course from the cantonal Veterinarämt. But honestly if you are new to dog ownership in CH I'd recommend taking the theory course, as things are rather different here.)
Wishing you and your new canine friend all the best.