Perhaps you should try some spelling variations:
"phuong toan du snippets" » "phong toan du snippets", "phuong tran du snippets", "phuong doan du snippets", "phuong tran duc snippets", "phuong toan cau snippets"
"using java code snippets" » "using data code snippets", "using java core snippets"
"locating bug code snippets" » "locating bug core snippets", "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: (((("using java code snippets") or ("phuong toan du snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("using java code snippets") OR ("phuong toan du snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( using java code snippets ) or ( phuong toan du snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("using java code snippets") or ("phuong toan du snippets"))) or ("locating bug code snippets"))*.