Perhaps you should try some spelling variations:
"van hoc code snippets" » "van hoc co snippets", "van hoc cong snippets", "van hoc de snippets", "van hoa code snippets", "van hoc code slippers"
"cong trinh java snippets" » "cong trinh java slippers"
"locating bug code snippets" » "locating bug code slippers", "locating bung code snippets", "locating bugs code 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: (((("cong trinh java snippets") or ("van hoc code snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("cong trinh java snippets") OR ("van hoc code snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( cong trinh java snippets ) or ( van hoc code snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("cong trinh java snippets") or ("van hoc code snippets"))) or ("locating bug code snippets"))*.