Perhaps you should try some spelling variations:
"nijhoff book titles 26" » "nijhoff boston titles 26", "nijhoff book entitled 26", "nijhoff book intitled 26", "nijhoff book titles 2.9", "nijhoff book titles _", "nijhoff book titles 1"
"nijhoff ebook title 20" » "nijhoff book title 20", "nijhoff ebook title 10", "nijhoff ebook title 21", "nijhoff ebook title 25", "nijhoff ebook title _0", "nijhoff ebook title a0"
"nijhoff ebook title 2" » "nijhoff book title 2", "nijhoff ebook title _", "nijhoff ebook title a", "nijhoff ebook title 1"
"nijhoff op titles 26" » "nijhoff _ titles 26", "nijhoff j titles 26", "nijhoff op titles 2.9", "nijhoff op titles _", "nijhoff op titles 1", "nijhoff up titles 26", "nijhoff comp titles 26", "nijhoff job titles 26"

Try widening your search to All Fields.

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 book titles 26") OR ("nijhoff op titles 26")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"nijhoff ebook title 20\") or (\"nijhoff ebook title 2\"))) or (((\"nijhoff book titles 26\") OR (\"nijhoff op titles 26\"))))".
• Removing quotes may allow a broader search: (((( nijhoff ebook title 20 ) or ( nijhoff ebook title 2 ))) or ((( nijhoff book titles 26 ) OR ( nijhoff op titles 26 )))).
• Adding a wildcard symbol may retrieve word variants: (((("nijhoff ebook title 20") or ("nijhoff ebook title 2"))) or ((("nijhoff book titles 26") OR ("nijhoff op titles 26"))))*.