Perhaps you should try some spelling variations:
"dung thuc cach snippets" » "dung thuc code snippets", "dung thuoc cach snippets", "duong thuc cach snippets", "dung thu cach snippets", "dung thuoc sach snippets", "dung truoc cach snippets", "dung thuc hanh snippets"
"locating bug core snippets" » "locating bug code snippets"
"dung java java snippets" » "dung va java snippets"

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (((("dung thuc cach snippets") or ("dung java java snippets"))) or ("locating bug core snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung thuc cach snippets") OR ("dung java java snippets"))) OR ("locating bug core snippets")).
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