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