Currently there is no way to search for a particular notebook. Searching only by notes brings confusion since you can have different notes with similar names and content in different notebooks.
The search box can be above All Notes on the notebooks sidebar:
Hi, might gotoanything help you with your use case?
Try the key combination
Ctrl+P "@notebook-name"
notebook name should be without quotes 
not sure if it can be a help, but there are lots of ways to filter a search: Searching | Joplin
just in case, you did not stumble upon that info yet
Just what I wanted thanks
