Perhaps you should try some spelling variations:
"trinh luan phan snippets" » "trinh luat phan snippets", "trinh quan phan snippets", "trinh han phan snippets", "trinh luan van snippets", "trinh luan hoan snippets"
"dung java java slippers" » "dung va java slippers", "dung java java slippery", "dung java java grippers"
"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 slippers") or ("trinh luan phan snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung java java slippers") OR ("trinh luan phan snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung java java slippers ) or ( trinh luan phan snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung java java slippers") or ("trinh luan phan snippets"))) or ("locating bug code snippets"))*.