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