Perhaps you should try some spelling variations:
"dung viec voi snippets" » "dung viet voi snippets", "dung vien voi snippets", "nhung viec voi snippets", "dung viec cuoi snippets", "dung viec va snippets", "dung viec so snippets"
"dung java java snippets" » "dung va java snippets"
"locating bug code snippets" » "locating bung code snippets", "locating bugs code snippets", "locating bug core snippets"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("dung viec voi snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung viec voi snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung viec voi snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung viec voi snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.