The quick search field lets you enter sub-strings that might be in author names, titles or dates, and the reference view will display only matching publications. There are several built-in options. For example, "Any Fields" (search every field except the pub type at once), and "Person", which searches Author, Editor, and any other field defined as a "Person" field in preferences.
The quick search field is configurable using its menu (click on the triangle in the text box). The default behavior is to do a simple substring search, but Advanced Search Options for Apple's Search Kit technology are available as well.