Perhaps you should try some spelling variations:
"multiple operations research : july 2006" » "multiple generations research : july 2006", "multiple migrations research : july 2006", "multiple options research : july 2006", "multiple operations research : july 2008", "multiple operations research : july 2007", "multiple operations research : july 2013"
"multiple national research : july 2009" » "multi national research : july 2009", "multiple natural research : july 2009", "multiple international research : july 2009", "multiple educational research : july 2009", "multiple national research : july 2008", "multiple national research : july 2007", "multiple national research : july 2019"

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("multiple national research : july 2009") or ("multiple operations research : july 2006"))~.
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