Perhaps you should try some spelling variations:
"nijhoff ebook title 20" » "nijhoff book title 20", "nijhoff book titles 20", "nijhoff ebook title 10", "nijhoff ebook title 25", "nijhoff ebook title 26", "nijhoff ebook title _0", "nijhoff ebook title a0"
"nijhoff ebook title 2" » "nijhoff book title 2", "nijhoff book titles 2", "nijhoff ebook title _", "nijhoff ebook title a", "nijhoff ebook title 1"
"nijhoff ebook title 21" » "nijhoff book title 21", "nijhoff book titles 21", "nijhoff ebook title 1", "nijhoff ebook title _", "nijhoff ebook title a", "nijhoff ebook title _1", "nijhoff ebook title a1", "nijhoff ebook title 11"
"nijhoff ebook title 5" » "nijhoff book title 5", "nijhoff book titles 5", "nijhoff ebook title _", "nijhoff ebook title a", "nijhoff ebook title 1"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((((("nijhoff ebook title 20") OR ("nijhoff ebook title 2"))) OR ("nijhoff ebook title 21"))) OR ("nijhoff ebook title 5")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"nijhoff ebook title 20\") OR (\"nijhoff ebook title 2\"))) or (\"nijhoff ebook title 21\"))) or (\"nijhoff ebook title 5\"))".
• Removing quotes may allow a broader search: (((((( nijhoff ebook title 20 ) OR ( nijhoff ebook title 2 ))) or ( nijhoff ebook title 21 ))) or ( nijhoff ebook title 5 )).
• Adding a wildcard symbol may retrieve word variants: (((((("nijhoff ebook title 20") OR ("nijhoff ebook title 2"))) or ("nijhoff ebook title 21"))) or ("nijhoff ebook title 5"))*.