If it is obvious that the book is on the shelf but can't be found:
Other readers are holding it, or just throwing it away after reading it. If the organizer can't find it, it can't be taken back. This kind of situation is generally not easy to find.
The new book has just arrived, and the materials have just been completed, but the book has been uploaded in batches, and it is possible that the book has not been finished. Usually it will be on the shelves in a few days.
It may have been eliminated, but the data has not been made into a computer. So you can't find it.
There are too many books on the shelf, which may need to be relocated, but the data has not been entered into the computer. This will have to wait, or look for it in the same category.
I didn't lend it out, I just returned it, so it will appear on the bookshelf (if it is not taken away by others first).
You can only reserve books that others are borrowing. The former person will be detained by the staff when he returns it. You can borrow it. Just check the status of the book on the website at any time.
Books that are not checked out can only be found by yourself ~ there are often books that cannot be found. If it is urgent, it is recommended to buy it to save time. If you are not in a hurry, you will usually look for them ~