Perhaps you should try some spelling variations:
"dung tran doan snippets" » "dung tran code snippets", "dung tren doan snippets", "hung tran doan snippets", "dang tran doan snippets", "dung trang doan snippets", "dung tan doan snippets", "dung tran 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 tran 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 tran doan snippets") OR ("dung java java snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( dung tran doan snippets ) or ( dung java java snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung tran doan snippets") or ("dung java java snippets"))) or ("locating bug core snippets"))*.