Perhaps you should try some spelling variations:
"multi operations research : july 2009" » "mutation operations research : july 2009", "poultry operations research : july 2009", "runtime operations research : july 2009", "multi operations research : july 2008", "multi operations research : july 2007", "multi operations research : july 2019"
"port operations research : july 2013" » "market operations research : july 2013", "transport operations research : july 2013"

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