Perhaps you should try some spelling variations:
"tran trinh code snippets" » "trang trinh code snippets", "tra trinh code snippets", "thanh trinh code snippets", "tran trinh cong snippets", "tran trinh co snippets", "tran trinh cad snippets"
"dung java java snippets" » "dung va java snippets"
"locating bug core snippets" » "locating bug code 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 ("tran trinh code snippets"))) or ("locating bug core snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung java java snippets") OR ("tran trinh code snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( dung java java snippets ) or ( tran trinh code snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung java java snippets") or ("tran trinh code snippets"))) or ("locating bug core snippets"))*.