Someone searched on free review Hereditary Spherocytosis.
Here’s a better strategy for finding only PDFs of review articles on a specific topic. Type m:text/pdf and then the search term. For example, the request above would be m:text/pdf hereditary spherocytosis.
This limits your search to PDFs.
Finding reviews only is more difficult, because sometimes the word "review" doesn't even appear in a review. (The journal may use a designation such as "Clinical Perspectives." You may be better off just scanning the titles for what appears to be a relevant review.)
Also, this strategy will not offer articles that are not put online in PDF format. You can tell whether a non-PDF result is full text by looking at the blue Internet address that appears immediately above the journal name and date. (It's clickable, by the way.)
Usually you'll see the word "full" somewhere inside that technical garble if the result provides the complete text.