Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
hanh vai » hanh vi, hanh va, hanh van
cua viet » hoa viet, cua vat, cua dieu
vien dai » hien dai
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
duc van » duc va, duc tan, duc manh
dai duc » dao duc, dai dua, mai duc
xang ma » tang ma, nang ma, sang ma
ca viet » va viet, co viet, hoa viet

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 ty xang ma hoa. hieu vien dai duc van ((hanh vai) or (hanh tai)) ((cua viet) or (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty xang ma hoa. hieu vien dai duc van ((hanh vai) OR (hanh tai)) ((cua viet) OR (ca viet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ty xang ma hoa. hieu vien dai duc van ((hanh vai) or (hanh tai)) ((cua viet) or (ca viet))*.