Perhaps you should try some spelling variations:
"nam van trac snippets" » "nam va trac snippets", "nam van thac snippets", "nam van tra snippets", "nam dan trac snippets", "pham van trac snippets", "nam van trac slippers"
"python using a snippets" » "python using a slippers"
"locating bug code snippets" » "locating bug code slippers", "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: (((("nam van trac snippets") or ("python using a snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("nam van trac snippets") OR ("python using a snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( nam van trac snippets ) or ( python using a snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("nam van trac snippets") or ("python using a snippets"))) or ("locating bug code snippets"))*.