Perhaps you should try some spelling variations:
"hedonic model" » "hedonico model", "hedonic modelo"
"hedonica model" » "hedonicoa model", "hedonica modelo", "hedonico model", "hedonista model", "veronica model"
"helenista model" » "helenista modelo", "helenistica model", "helenismo model", "elenita model"
"helenico model" » "helenico modelo", "helenica model", "helenismo model", "edenico model"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("hedonic model") OR ((((("hedonica model") OR ("helenista model"))) OR ("helenico model"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"hedonic model\") OR (((((\"hedonica model\") OR (\"helenista model\"))) OR (\"helenico model\"))))".
• Removing quotes may allow a broader search: (( hedonic model ) OR ((((( hedonica model ) OR ( helenista model ))) OR ( helenico model )))).
• Adding a wildcard symbol may retrieve word variants: (("hedonic model") OR ((((("hedonica model") OR ("helenista model"))) OR ("helenico model"))))*.