These are tough. I get lots of hits at Google for the first two, but not many texts, especially for Kudrun. That may be because the work is known from a single text whose authenticity seems to be debatable. I found an english version of Widsith here and an original here, both at Georgetown. Berkeley has an english Saxo Grammaticus(the first 9 books, apparently there is no public domain version of the rest), with a link to an original. For Kudrun, alas, I can only find articles about the poem and various books for sale. Hope this helps some.