The are currently on-line, and do searchs through the lists that are out there. BUT, there is seldom a good way to post a wanted book.
(One of the services, I think ABE, has 20,000 Andre Norton listings. I didn't try to check them all, but did a search using the titles.)

My local shop suggests that I use AB Bookman's because it is still out there, and book dealers are using it to post and sell their stock. In fact, my local dealer still sells books to requests from AB Bookman's.

I have had Amazon.com order me a book that I had requested months ago, even though it was not in stock. But, there is no way to request an obscure book, like these paper editions are. If they can be found, these may be sitting on the shelf in a book store that specializes in childrens books. Probably my best hope is somewhere in the Mid-west, since that is where the original publisher was.

Another possibility is that one of the libraries have copies. I may try posting to the on-line library catalogues. Just to look at copies.