Perhaps you should try some spelling variations:
"nha thuoc sach snippets" » "nha hoc sach snippets", "nha nuoc sach snippets", "nha thuat sach snippets", "nhan thuc sach snippets", "nha thuoc sach slippers"
"python using a snippets" » "python using a slippers"
"locating bug code snippets" » "locating bug code slippers", "locating bung code snippets", "locating bugs code snippets", "locating bug core snippets"

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (((("nha thuoc sach snippets") or ("python using a snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("nha thuoc sach snippets") OR ("python using a snippets"))) OR ("locating bug code snippets")).
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• Adding a wildcard symbol may retrieve word variants: (((("nha thuoc sach snippets") or ("python using a snippets"))) or ("locating bug code snippets"))*.