Perhaps you should try some spelling variations:
"trung trac hoc snippets" » "trung tran hoc snippets", "trung truc hoc snippets", "truong trai hoc snippets", "trung toan hoc snippets", "trung thai hoc snippets", "trung toc hoc snippets"
"dung java java slippery" » "dung va java slippery", "dung java java slippers"
"locating bug code snippets" » "locating bung code snippets", "locating bugs code snippets", "locating bug core snippets"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"dung java java slippery\") OR (\"trung trac hoc snippets\"))) OR (\"locating bug code snippets\"))~".
• Removing quotes may allow a broader search: (((( dung java java slippery ) OR ( trung trac hoc snippets ))) OR ( locating bug code snippets ))~.
• Adding a wildcard symbol may retrieve word variants: (((("dung java java slippery") OR ("trung trac hoc snippets"))) OR ("locating bug code snippets"))*.