Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
tinh hai » tinh thai, tinh chat, trinh han
hieu van » hieu va, thien van, lieu va
hai cua » thai cua, dai cua, hoi cua
va tinh » may tinh
cac duc » cac du, cao duc, cac dac
van cac » van hac, van cau, van bac
sach ty » sach y, sach thu, xach tay
cao hoi » cau hoi, co hoi, tao hoi
sach tu » sach thu, cach tu, sach uu
cao hoc » co hoc, cho hoc, chat hoc

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: te ((sach ty) OR (sach tu)) nang ((cao hoi) OR (cao hoc)). hieu van cac duc va tinh hai cua viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) OR (sach tu)) nang ((cao hoi) or (cao hoc)). hieu van cac duc va tinh hai cua viet~".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) OR (sach tu)) nang ((cao hoi) or (cao hoc)). hieu van cac duc va tinh hai cua viet*.