Perhaps you should try some spelling variations:
thanh tung » thanh cong
hieu cach » hieu cac, chieu sach, hieu ca
khoan cam » khoa cam, khoan va, phan cam
doc hieu » toc thieu, hoc thieu, hoc hien
tung cua » trung cua, tuong cua, dung cua
dong ban » dong bang, dong san, dong bac
khan cap » khan ap, phan cac, phan cau
than cap » thanh lap, thanh cac, than cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu cach - thanh tung cua cong dong ban ((((khan cap) OR (khoan cam))) OR (than cap))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu cach - thanh tung cua cong dong ban ((((khan cap) OR (khoan cam))) or (than cap))~".
• Adding a wildcard symbol may retrieve word variants: doc hieu cach - thanh tung cua cong dong ban ((((khan cap) OR (khoan cam))) or (than cap))*.