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