Perhaps you should try some spelling variations:
trung tuan » trung thanh, trung tam, tran tuan
thong cong » trong cong, tong cong, thong thong
hieu cach » hieu cac, chieu sach, hieu ca
trung cap » truong cao, trung tam
doc hieu » toc thieu, hoc thieu, hoc hien
cong dan » cong san, cong tan, huong dan
dan khan » dan khanh, dan chan, dan than
khan cap » khan ap, than cap, khoan cam

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 ((trung tuan) or (trung cap)) thong cong dan khan cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu cach - thanh ((trung tuan) OR (trung cap)) thong cong dan khan cap*.