Perhaps you should try some spelling variations:
"multi sciences research : july 2013" » "multi science research : july 2013", "aquatic sciences research : july 2013"
"multiple opinion research : july 2007" » "multiple options research : july 2007", "multiple positions research : july 2007", "multiple decision research : july 2007", "multiple action research : july 2007", "multiple opinion research : july 2008", "multiple opinion research : july 2012", "multiple opinion research : july 2020"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"multi sciences research : july 2013\") OR (\"multiple opinion research : july 2007\"))~".
• Removing quotes may allow a broader search: (( multi sciences research : july 2013 ) OR ( multiple opinion research : july 2007 ))~.
• Adding a wildcard symbol may retrieve word variants: (("multi sciences research : july 2013") OR ("multiple opinion research : july 2007"))*.