Perhaps you should try some spelling variations:
"cong trinh luan van thu dong cua ban" » "cong trinh luat van thu dong cua ban", "cong trinh quan van thu dong cua ban", "cong trinh toan van thu dong cua ban", "cong trinh luan van thuy dong cua ban", "cong trinh luan van tu dong cua ban", "cong trinh luan van thu cong cua ban", "cong trinh luan van thu dung cua ban", "cong trinh luan van thu huong cua ban"
"cong trinh han van thu dong cua ban" » "cong trinh quan van thu dong cua ban", "cong trinh han van thuy dong cua ban", "cong trinh han van tu dong cua ban", "cong trinh han van thu cong cua ban", "cong trinh han van thu dung cua ban", "cong trinh han van thu huong cua ban", "cong trinh phan van thu dong cua ban", "cong trinh nhan van thu dong cua ban", "cong trinh hanh van thu dong 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 dong cua ban") OR ("cong trinh han van thu dong cua ban"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"cong trinh luan van thu dong cua ban\") OR (\"cong trinh han van thu dong cua ban\"))".
• Removing quotes may allow a broader search: (( cong trinh luan van thu dong cua ban ) OR ( cong trinh han van thu dong cua ban )).
• Adding a wildcard symbol may retrieve word variants: (("cong trinh luan van thu dong cua ban") OR ("cong trinh han van thu dong cua ban"))*.