Perhaps you should try some spelling variations:
"trinh luan hoc snippets" » "trinh luat hoc snippets", "trinh quan hoc snippets", "trinh han hoc snippets", "trinh luan hoan snippets", "trinh quang hoc snippets", "trinh luan khoa snippets"
"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 java java snippets") or ("trinh luan hoc snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung java java snippets") OR ("trinh luan hoc snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung java java snippets ) or ( trinh luan hoc snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung java java snippets") or ("trinh luan hoc snippets"))) or ("locating bug code snippets"))*.