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Boolean operators (and, or, not), Nesting with parentheses, and Truncation symbols (*) can be used to develop more complex search queries. These queries can be entered directly into the Search box. Quotation marks can be used around phrases to retrieve documents containing the exact phrase.
retrieval set includes coverage of birth defect or birth defects
birth defects and folic acid
retrieval set includes content covering birth defects and folic acid in the same document
birth defects or folic acid
retrieval set includes either content covering birth defects or content covering folic acid
birth defects not folic acid
retrieval set includes content that covers birth defects where folic acid is not covered in the document
(neural tube defects or birth defects) and folic acid
retrieval set includes content where either neural tube defects or birth defects is covered and prevention with folic acid is covered in all content
retrieval set includes content where the exact phrase neural tube appears in the document