Perhaps you should try some spelling variations:
"python missing data snippets" » "python using data snippets"
"locating bug core snippets" » "locating bug code snippets"
"o viet dat snippets" » "o viec dat snippets", "o viet da snippets", "o viet dao snippets", "so viet dat snippets", "hoc viet dat snippets"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("o viet dat snippets") or ("python missing data snippets"))) or ("locating bug core snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("o viet dat snippets") OR ("python missing data snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( o viet dat snippets ) or ( python missing data snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("o viet dat snippets") or ("python missing data snippets"))) or ("locating bug core snippets"))*.