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