Perhaps you should try some spelling variations:
"duong dan cach snippets" » "duong dang cach snippets", "huong dan cach snippets", "duong van cach snippets", "duong dan cac snippets", "duong dan canh snippets", "duong nhan cach snippets"
"dung java java snippets" » "dung va java snippets"
"locating bug code snippets" » "locating bung code snippets", "locating bugs code snippets", "locating bug core 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: (((("duong dan cach snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("duong dan cach snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( duong dan cach snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("duong dan cach snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.