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