Perhaps you should try some spelling variations:
"multiple operations research : july 2009" » "multiple generations research : july 2009", "multiple migrations research : july 2009", "multiple options research : july 2009", "multiple operations research : july 2008", "multiple operations research : july 2007", "multiple operations research : july 2019"
"multiple opinion research : july 2009" » "multiple options research : july 2009", "multiple positions research : july 2009", "multiple decision research : july 2009", "multiple action research : july 2009", "multiple opinion research : july 2008", "multiple opinion research : july 2007", "multiple opinion research : july 2019"

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