Perhaps you should try some spelling variations:
"dung ninh viet slippers" » "dung vinh viet slippers", "quang ninh viet slippers", "dung dich viet slippers", "dung sinh vien slippers", "dung anh viet slippers", "dung ninh viet slippery", "dung ninh viet grippers"
"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 ninh viet slippers") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung ninh viet slippers") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung ninh viet slippers ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung ninh viet slippers") or ("dung java java snippets"))) or ("locating bug code snippets"))*.