Perhaps you should try some spelling variations:
"dung doan viet slippers" » "dung doanh viet slippers", "dung dan viet slippers", "dung toan viet slippers", "dung khoan viet slippers", "dung doan viet slippery", "dung doan 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 doan 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 doan viet slippers") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung doan viet slippers ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung doan viet slippers") or ("dung java java snippets"))) or ("locating bug code snippets"))*.