Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hieu cach » hieu cac, chieu sach, hieu ca
doc hieu » toc thieu, hoc thieu, hoc hien
trang va » hang va
tran van » luan van
cong ban » cong bang, cong san, cong tan
than cau » toan cau, phan cau, thanh chau
than cap » khan cap, thanh lap, thanh cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu cach - hanh ((trang va) or (tran van)) nhung cong ban ((than cau) OR (than cap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu cach - hanh ((trang va) OR (tran van)) nhung cong ban ((than cau) OR (than cap)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu cach - hanh ((trang va) or (tran van)) nhung cong ban ((than cau) OR (than cap))".
• Adding a wildcard symbol may retrieve word variants: doc hieu cach - hanh ((trang va) or (tran van)) nhung cong ban ((than cau) OR (than cap))*.