Perhaps you should try some spelling variations:
thanh tung » thanh cong
hieu cach » hieu cac, chieu sach, hieu ca
hang cong » dang cong, hang nong, bang cong
doc hieu » toc thieu, hoc thieu, hoc hien
tung cao » nung cao, truong cao, trung cap
cao hang » cao dang, cao tang, cao bang
van than » van thanh, van thang, van tuan

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 - thanh tung cao hang cong ((xuan toan) or (van than)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu cach - thanh tung cao hang cong ((xuan toan) OR (van than)) cao.
• Adding a wildcard symbol may retrieve word variants: doc hieu cach - thanh tung cao hang cong ((xuan toan) or (van than)) cao*.