Perhaps you should try some spelling variations:
"mang viet cong snippets" » "nang viet cong snippets", "anh viet cong snippets", "mai viet cong snippets", "mang viet cuong snippets", "mang viec cong snippets", "mang viet dong 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 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: (((("mang viet cong snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( mang viet cong snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("mang viet cong snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.