Irish and Swiss?
General tip:
the public library is your best friend, and if you have a university library, that's even better! (sorry guys, but real research is not "I searched the internet"). Browse the shelves yourself, talk to a librarian there for research help, and don't be afraid to interlibrary loan. In particular, you'll want to pop up keywords like "Celtic," "Gaelic," also "Nordic/Norse," "Anglo-Saxon," and "Germanic." You're basically going to be looking into Celtic and Nordic mythology, so you could scout some of those references ala the proper dewey or library of congress codes, and I know there are also plenty of works out there on both Irish and Germanic folklore. Histories of the region can be insightful as well.
Fore Ireland in particular, there's a great scholar I know of in particular that specializes in the British Isles. His name is Ronald Hutton, and
this book "Pagan Religions of the Ancient British Isles" (amazon link) should definitely be on your reading list. He also has another book out on druidry specifically, if you are particularly curious about that sort of thing.
Switzerland is a bit more challenging, because from what little I know, it's geographic position made it quite multicultural. Some of their Pagan history is Germanic, but they also had some Roman influences in later eras. Honestly, I've little doubt someone has a collection of the folklore of that region, but I'm not personally familiar with it.
