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