In case anyone else is interested, an alert on Cloudy Night brought this to my attention, Luna Cognita as PDF or EPUB discounted at the moment to €16.99.
https://link.springer.com/book/10.10...-1-4939-1664-1
Not the same as having it in hand, but still great to have. I bought it yesterday. But be aware, the download is over 1GB. My iPad couldn’t handle it, so had to get it on the desktop.