I see Wolf Hirth's The Art of Soaring Flight mentioned a number of times. If you are reading it in English it was translated by a Naomi Heron-Maxwell. It is a bit different from the German because of her input and Doc Slater. The book about her flying is called Naomi the Aviatrix. More chick flick than how to soar so if you don't like it, re-gift it to the wife! https://sites.google.com/site/naomitheaviatrix/