Academic sources on freesking

Made this thread in ski gabber also but might as well put it here too. So i'm doing a presentation on freestyle skiing but we need to have academic sources for all of our information. That means no wikipedia, so where can I find a source that could even kind of be considered academic? Of course I used google and found this http://www.lib.utah.edu/collections/ski-archives/ where they mention these fabled ski archives but I can't actually find them. Any help would be appreciated, really don't want to change my topic