I have not read the Markowski book. It just read an absolutely destructive review of Markowski here that is really worth reading if you like Saisons. I did not fact check the fact checker. The comments in this page do some great counter points however.
Garshol book is not one person's take on a regional style. Instead he is interviewing the actual "farmers" who are making beer and maintain family practices. So there is no one origin.
What is really distinctive, as we all nerd out on gear and best practices to push magical boundaries, is how raw beer making can be. For example...