Perhaps you should try some spelling variations:
"truong thanh he snippets" » "truong trung he snippets", "truong thpt he snippets", "truong chung he snippets", "truong thanh hue snippets", "truong thanh ha snippets", "truong thanh ve 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 ("truong thanh he snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dung java java snippets") OR ("truong thanh he snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dung java java snippets ) or ( truong thanh he snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dung java java snippets") or ("truong thanh he snippets"))) or ("locating bug code snippets"))*.