Perhaps you should try some spelling variations:
"multiple imputation research : july 2013" » "multiple mutation research : july 2013", "multiple reputation research : july 2013", "multiple population research : july 2013"
"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"

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• Performing a fuzzy search may retrieve terms with similar spellings: (("multiple imputation research : july 2013") or ("multi operations research : july 2009"))~.
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