Perhaps you should try some spelling variations:
"cong khung hoc snippets" » "cong chung hoc snippets", "cong hung hoc snippets", "cong khong hoc snippets", "cong nhung hoc snippets", "cong thuong hoc 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 ("cong khung 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 ("cong khung hoc snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung java java snippets ) or ( cong khung hoc snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung java java snippets") or ("cong khung hoc snippets"))) or ("locating bug code snippets"))*.