Perhaps you should try some spelling variations:
"dung viet doan snippets" » "dung viet code snippets", "nang viet doan snippets", "cong viet doan snippets", "mang viet doan snippets", "dung viet hoan snippets", "dung viet hoang snippets", "dung viet van snippets"
"locating bug core snippets" » "locating bug code snippets"
"dung java java snippets" » "dung va java 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 viet doan snippets") or ("dung java java snippets"))) or ("locating bug core snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung viet doan snippets") OR ("dung java java snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( dung viet doan snippets ) or ( dung java java snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung viet doan snippets") or ("dung java java snippets"))) or ("locating bug core snippets"))*.