Another book that elaborates at some length on non-instrument navigation and the evidence for it is Pathway of the Birds. https://www.goodreads.com/book/show/41

Another book that elaborates at some length on non-instrument navigation and the evidence for it is Pathway of the Birds. https://www.goodreads.com/book/show/41112497-pathway-of-the-birds https://www.goodreads.com/book/show/41112497-pathway-of-the-...