Perhaps you should try some spelling variations:
"dung van toan snippets" » "dung van code snippets", "duong van toan snippets", "dung va toan snippets", "dang van toan snippets", "dung van tuan snippets", "dung van tan snippets", "dung van thanh 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 van toan 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 van toan snippets") OR ("dung java java snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( dung van toan snippets ) or ( dung java java snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung van toan snippets") or ("dung java java snippets"))) or ("locating bug core snippets"))*.