Perhaps you should try some spelling variations:
"duong thuc so snippets" » "luong thuc so snippets", "duong thu so snippets", "duong thuy so snippets", "duong thuoc so snippets", "duong thuc co snippets", "duong thuc su 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 thuc so 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 thuc so snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( duong thuc so snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("duong thuc so snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.