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

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 21 ) 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 21 ) 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 21 ) OR ( nijhoff book entitled 21 ))) or ( nijhoff boston titles 21 ))) or ( nijhoff book title 26 ))))*.