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