Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
nang dau » hang dau, xang dau, nang du
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
cam luc » cam xuc, cau luc
van cam » van nam, van lam, van cau
sach ky » sac ky, sach y, sach kem
dau hoi » cau hoi, dai hoi, dan hoi
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
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) or (sach ty)) nang dau hoi. hieu van cam luc va hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang dau hoi. hieu van cam luc va hanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach ty)) nang dau hoi. hieu van cam luc va hanh tai cua tre*.