Perhaps you should try some spelling variations:
thanh trung » thanh tung
dang phuong » bang phuong, dung phuong, dan phuong
phuong tinh » phuong trinh, phuong binh, khuong tinh
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
cua dang » cua cong, cua ban
toan ban » van ban

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 sang) or (hieu lang)) - thanh trung cua dang phuong tinh ((toan tap) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu lang)) - thanh trung cua dang phuong tinh ((toan tap) OR (toan ban)).
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu lang)) - thanh trung cua dang phuong tinh ((toan tap) or (toan ban))*.