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