Perhaps you should try some spelling variations:
"cong trinh luan van thu dang cua ban" » "cong trinh quan van thu dang cua ban", "cong trinh han van thu dang cua ban", "cong trinh toan van thu dang cua ban", "cong trinh luan van thu hang cua ban", "cong trinh luan van thu bang cua ban", "cong trinh luan van thu dong cua ban", "cong trinh luan van thu dung cua ban", "cong trinh luan van thu mang cua ban"
"cong trinh luat van thu dang cua ban" » "cong trinh luat van thu hang cua ban", "cong trinh luat van thu bang cua ban", "cong trinh luat van thu dong cua ban", "cong trinh luat van thu dung cua ban", "cong trinh luat van thu mang cua ban", "cong trinh luat dan thu dang cua ban", "cong trinh luat va thu dang cua ban", "cong trinh luat ban thu dang cua ban"

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