Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien can » vien canh, vien cac, vien cao
can nuoc » cap nuoc, cac nuoc, can cuoc
cua viet » ca viet, hoa viet, cua dieu
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
mai hoi » mai khoi, dai hoi, mai doi
lai hoi » dai hoi, lai hoa, lai roi
va hanh » van hanh, va thanh, va danh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach tu nang ((mai hoi) or (lai hoi)). hieu vien can nuoc va hanh vi ((cua viet) OR (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nang ((mai hoi) OR (lai hoi)). hieu vien can nuoc va hanh vi ((cua viet) OR (cua vat)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu nang ((mai hoi) or (lai hoi)). hieu vien can nuoc va hanh vi ((cua viet) OR (cua vat))".
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang ((mai hoi) or (lai hoi)). hieu vien can nuoc va hanh vi ((cua viet) OR (cua vat))*.