Perhaps you should try some spelling variations:
"tra trinh dan slippers" » "qua trinh dan slippers", "tra trinh han slippers", "tra trinh van slippers", "tra trinh san slippers", "tra trinh dan slippery", "tra trinh dan 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: (((("tra trinh dan slippers") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("tra trinh dan slippers") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( tra trinh dan slippers ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("tra trinh dan slippers") or ("dung java java snippets"))) or ("locating bug code snippets"))*.