Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, dien sach
trung cap » truong cao
hang cong » dang cong, hang nong, bang cong
hieu cac » hieu luc, hieu va, hieu van
cong tan » cong tac, cong san, cong thanh
tan thai » tay thai, ban thai, tan tai
thai cao » tai cao, thoai cac, thuat cao

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 sach) OR (hieu cac)) - manh ((trung cap) OR (trung tam)) hang cong tan thai cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sach) or (hieu cac)) - manh ((trung cap) OR (trung tam)) hang cong tan thai cao~".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sach) or (hieu cac)) - manh ((trung cap) OR (trung tam)) hang cong tan thai cao*.