Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nang tai » hang tai, sang tai, nang cao
hanh vai » hanh vi, hanh va, hanh tai
tang tai » hang tai, dung tai, sang tao
su sach » so sach, vu sach
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
cam luc » cam xuc, cau luc
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
luc va » duc va, tuc va, loc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang tai) or (tang tai)) roi. ((hieu ve) OR (hieu van)) cam luc va hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang tai) OR (tang tai)) roi. ((hieu ve) OR (hieu van)) cam luc va hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang tai) or (tang tai)) roi. ((hieu ve) OR (hieu van)) cam luc va hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang tai) or (tang tai)) roi. ((hieu ve) OR (hieu van)) cam luc va hanh vai cua tre*.