Perhaps you should try some spelling variations:
"cong trinh luan snippets" » "cong trinh luat snippets", "cong trinh quan snippets", "cong trinh han snippets", "cong trinh luan slippers"
"dung cac code snippets" » "luong cac code snippets", "dung cho code snippets", "dung tai code snippets", "dung cac cong snippets", "dung cac co snippets", "dung cac che snippets", "dung cac code slippers"
"locating bug code snippets" » "locating bug code slippers", "locating bung code snippets", "locating bugs code 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: (((("cong trinh luan snippets") or ("dung cac code snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("cong trinh luan snippets") OR ("dung cac code snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( cong trinh luan snippets ) or ( dung cac code snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("cong trinh luan snippets") or ("dung cac code snippets"))) or ("locating bug code snippets"))*.