Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
nhanh tai » nhanh thai, nhan tai, thanh tai
vien cac » vien bach, vien dai, vien da
hanh tai » thanh tai, hang tai, han tai
xuc ban » duc ban, cuc ban, quoc ban
tu sach » thu sach, su sach, te sach
cac xuc » cam xuc, cac nuoc, chat xuc
sach ky » sac ky, sach y, sach ty
nang ro » nang ho, nang ra, nang rong
nang co » nang cao, nang doc, nang noi
cua tre » cua te, cuu tre, cua triet

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 co) or (nang ro)) hai. hieu vien cac xuc ban ((hanh tai) or (nhanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang co) OR (nang ro)) hai. hieu vien cac xuc ban ((hanh tai) OR (nhanh tai)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang co) or (nang ro)) hai. hieu vien cac xuc ban ((hanh tai) or (nhanh tai)) cua tre*.