Perhaps you should try some spelling variations:
"dung tin toan snippets" » "dung tin code snippets", "dong tin toan snippets", "luong tin toan snippets", "dung tren toan snippets", "dung tinh toan snippets", "dung nin toan snippets", "dung trinh toan 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 ("dung tin 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 ("dung tin toan snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( dung java java snippets ) or ( dung tin toan snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung java java snippets") or ("dung tin toan snippets"))) or ("locating bug core snippets"))*.