UT Orpheus Edizioni have just published '3 Studies Op.88' for solo guitar. For several years only two of these Studies were known about and it was only after a search through the Guitar Foundation of America (GFA) library that a third Study was discovered. They have been carefully re-edited by Brian Roberts and are available here, or through your local supplier.

https://www.utorpheus.com/index.php?route=product/product&product_id=3709