Perhaps you should try some spelling variations:
"dong quoc hoc snippets" » "dang quoc hoc snippets", "dong duoc hoc snippets", "hoang quoc hoc snippets", "dong quoc hoi snippets", "dong buoc hoc 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: (((("dong quoc hoc snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("dong quoc hoc snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( dong quoc hoc snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("dong quoc hoc snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.