Perhaps you should try some spelling variations:
nerve investigation » re investigation, fire investigation, wave investigation
node investigation » bone investigation, close investigation, probe investigation
de investigacion » la investigacion
seis estudios » pacis estudios, los estudios, tres estudios
estudios de » estudio de

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