Perhaps you should try some spelling variations:
"mang viet so snippets" » "nang viet so snippets", "anh viet so snippets", "mai viet so snippets", "mang viec so snippets", "mang viet o snippets", "mang viet co 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: (((("mang viet so snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("mang viet so snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( mang viet so snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("mang viet so snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.