Perhaps you should try some spelling variations:
"cong thac luan van." » "cong thuc luan van." (Expand Search), "cong thao luan van." (Expand Search), "cong than luan van." (Expand Search), "cong tham luan van." (Expand Search)
"cong tac luan van." » "cong bac luan van." (Expand Search), "cong toc luan van." (Expand Search), "cong thuc luan van." (Expand Search)
"cong tac quan van." » "cong tac van van." (Expand Search), "cong tac quan va." (Expand Search), "cong tac quan hoan." (Expand Search), "cong tac quan lang." (Expand Search)

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: (((("cong tac luan van.") OR ("cong thac luan van."))) OR ("cong tac quan van."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"cong tac luan van.\") OR (\"cong thac luan van.\"))) OR (\"cong tac quan van.\"))".
• Removing quotes may allow a broader search: (((( cong tac luan van. ) OR ( cong thac luan van. ))) OR ( cong tac quan van. )).
• Adding a wildcard symbol may retrieve word variants: (((("cong tac luan van.") OR ("cong thac luan van."))) OR ("cong tac quan van."))*.