Perhaps you should try some spelling variations:
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"colloque, congres a conference _ le xvie siecle" » "colloque, congres _ conference _ le xvie siecle" (Expand Search), "colloque, congres di conferenze _ le xvie siecle" (Expand Search), "colloque, congres a conference _ le xvie siecles" (Expand Search), "colloque, congres a conference _ le xviiie siecle" (Expand Search), "colloque, congres a conference _ le xxe siecle" (Expand Search), "colloque, congress _ conference _ le xvie siecle" (Expand Search)

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• Performing a fuzzy search may retrieve terms with similar spellings: (("colloque, congres et conferences sur le xxe siecles") or ((("colloque, congres a conference sur le xvie siecle") or ("colloque, congres a conference _ le xvie siecle"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("colloque, congres et conferences sur le xxe siecles") OR ((("colloque, congres a conference sur le xvie siecle") OR ("colloque, congres a conference _ le xvie siecle")))).
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• Adding a wildcard symbol may retrieve word variants: (("colloque, congres et conferences sur le xxe siecles") or ((("colloque, congres a conference sur le xvie siecle") or ("colloque, congres a conference _ le xvie siecle"))))*.