Perhaps you should try some spelling variations:
"using tren cong snippets" » "sinh tren cong snippets", "song tren cong snippets", "using open cong snippets", "using trien cong snippets", "using tien cong snippets", "using tran cong 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: (((("using tren cong snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("using tren cong snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( using tren cong snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("using tren cong snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.