Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
ban hanh » ban hang
duc ban » duc tan, duc van, dua ban
cam duc » cam xuc, cao duc, pham duc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
ca viet » va viet, co viet, hoa viet
ma hoi » mai hoi, xa hoi, ma hoa

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 ky nang ma hoi. ((hieu vien) or (hieu hien)) cam duc ban hanh vi ((cua vat) or (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. ((hieu vien) OR (hieu hien)) cam duc ban hanh vi ((cua vat) OR (ca viet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. ((hieu vien) or (hieu hien)) cam duc ban hanh vi ((cua vat) or (ca viet))*.