Perhaps you should try some spelling variations:
"using java code snippets" » "using data code snippets", "using java core snippets"
"truong thpt do snippets" » "truong thpt dong snippets", "truong thuat do snippets", "truong thpt dan 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 ("truong thpt do snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("using java code snippets") OR ("truong thpt do snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( using java code snippets ) or ( truong thpt do snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("using java code snippets") or ("truong thpt do snippets"))) or ("locating bug code snippets"))*.