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Summon will usually be your best starting point for finding articles, books and dissertations.
You may also want to run supplementary searches in these databases:
For introductory articles:
The focus of the SIA collections, and of this guide, is English-language or bilingual material. However if you read Spanish or Portuguese, it is worth running searches in those languages too. For instance you could search for "arte contemporáneo mexicano" as well as “Mexican contemporary art”. You can do this in Summon, Art & Architecture Source, the catalogues of other libraries, or any other databases.