Perhaps you should try some spelling variations:
"cong viet can snippets" » "cong viec can snippets", "thong viet can snippets", "nang viet can snippets", "cong viet van snippets", "cong viet ca snippets", "cong vien can 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 viet can 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 viet can snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( cong viet can snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("cong viet can snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.