Perhaps you should try some spelling variations:
de investigaciones » de investigacion, la investigacion
y investigacion » e investigacion, la investigacion, de investigacion
pacis studies » species studies, pacific studies, packet studies
estudios y » estudios de, estudios en, studios _

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: (( de estudios y investigacion ) OR ( ((pacis estudios) OR (pacis studies)) de investigaciones )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( de estudios y investigacion ) or ( ((pacis estudios) OR (pacis studies)) de investigaciones ))".
• Adding a wildcard symbol may retrieve word variants: (( de estudios y investigacion ) or ( ((pacis estudios) OR (pacis studies)) de investigaciones ))*.