Perhaps you should try some spelling variations:
"using java core snippets" » "using data core snippets"
"tran mach cao snippets" » "tran manh cao snippets", "trinh mach cao snippets", "trong mach cao snippets", "tran mac ca snippets", "tran sach cap snippets", "tran mach lac snippets"
"locating bug code 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 core snippets") or ("tran mach cao snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("using java core snippets") OR ("tran mach cao snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( using java core snippets ) or ( tran mach cao snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("using java core snippets") or ("tran mach cao snippets"))) or ("locating bug code snippets"))*.