Perhaps you should try some spelling variations:
"nijhoff boston titles 21" » "nijhoff boston tables 21", "nijhoff boston times 21", "nijhoff boston entitled 21", "nijhoff boston titles 1", "nijhoff boston titles 71", "nijhoff boston titles 2.9"
"nijhoff work titles 11" » "nijhoff op titles 11", "nijhoff works titles 11", "nijhoff work title 11", "nijhoff works title 11", "nijhoff work titles 1", "nijhoff work titles 19", "nijhoff work titles 12"
"nijhoff book titles 11" » "nijhoff op titles 11", "nijhoff book intitled 11", "nijhoff book tables 11", "nijhoff work titles 11", "nijhoff book times 11", "nijhoff book titles 1", "nijhoff book titles 19", "nijhoff book titles 12"
"nijhoff book entitled 21" » "nijhoff op entitled 21", "nijhoff book entitled 1", "nijhoff book entitled _", "nijhoff book entitled a"
"nijhoff book title 26" » "nijhoff op title 26", "nijhoff book table 26", "nijhoff work title 26", "nijhoff book time 26", "nijhoff book title 2", "nijhoff book title 21", "nijhoff book title 25"
"nijhoff ebook title 2006" » "nijhoff ebook title 20", "nijhoff ebook title 2012", "nijhoff ebook table 2006", "nijhoff ework title 2006", "nijhoff ebook time 2006"
"nijhoff ebola time 2006" » "nijhoff ebola time 2000", "nijhoff ebola time 2001", "nijhoff ebola time 2004"

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 2006") OR ("nijhoff ebola time 2006"))) OR ((((((((("nijhoff book titles 11") OR ("nijhoff work titles 11"))) OR ("nijhoff book entitled 21"))) OR ("nijhoff boston titles 21"))) OR ("nijhoff book title 26")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"nijhoff ebook title 2006\") or (\"nijhoff ebola time 2006\"))) or (((((((((\"nijhoff book titles 11\") OR (\"nijhoff work titles 11\"))) or (\"nijhoff book entitled 21\"))) or (\"nijhoff boston titles 21\"))) or (\"nijhoff book title 26\"))))".
• Removing quotes may allow a broader search: (((( nijhoff ebook title 2006 ) or ( nijhoff ebola time 2006 ))) or ((((((((( nijhoff book titles 11 ) OR ( nijhoff work titles 11 ))) or ( nijhoff book entitled 21 ))) or ( nijhoff boston titles 21 ))) or ( nijhoff book title 26 )))).
• Adding a wildcard symbol may retrieve word variants: (((("nijhoff ebook title 2006") or ("nijhoff ebola time 2006"))) or ((((((((("nijhoff book titles 11") OR ("nijhoff work titles 11"))) or ("nijhoff book entitled 21"))) or ("nijhoff boston titles 21"))) or ("nijhoff book title 26"))))*.