Perhaps you should try some spelling variations:
"treatise depressive disorders" » "reactive depressive disorders", "treating depression disorders", "theorie depressive disorders"
"mail's depressive disorder" » "mail's impressive disorder", "mild depressive disorder", "manisch depressive disorder"

Try widening your search to All Fields.

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("mail's depressive disorder") OR ("treatise depressive disorders")).
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