Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh tai, hanh van
mai khoi » mai khoa, tai khoa, cac khoi
hanh va » hang va, hanh vi
cam tuc » cam xuc, cam tu, nam thuc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
ky tang » ky nang, ky dang, kho tang
van cam » van nam, van lam, van cau
tuc va » thuc va, truc va, tuc xa

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 tang ((mai hoi) or (mai khoi)). hieu van cam tuc va ((hanh vai) or (hanh va)) dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky tang ((mai hoi) OR (mai khoi)). hieu van cam tuc va ((hanh vai) OR (hanh va)) dau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang ((mai hoi) or (mai khoi)). hieu van cam tuc va ((hanh vai) or (hanh va)) dau tren*.