Perhaps you should try some spelling variations:
thanh trung » thanh tung
trung quan » truong quan, trong quan, trung tuan
quan dung » quang dung, quan duong, qua dung
dung cong » dung trong
nhanh bac » nhanh ha, nhanh va
doc hieu » toc thieu, hoc thieu, hoc hien
cong ban » cong bang, cong san, cong tan
hanh cac » hang cac, hanh cat, hanh cham

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 qua - thanh trung quan dung cong ban ((hanh cac) or (nhanh bac))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu qua - thanh trung quan dung cong ban ((hanh cac) OR (nhanh bac)).
• Adding a wildcard symbol may retrieve word variants: doc hieu qua - thanh trung quan dung cong ban ((hanh cac) or (nhanh bac))*.