Perhaps you should try some spelling variations:
nang cau » nang cao, hang cau, nang dau
tinh tai » trinh tai, tinh thai, tinh hai
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
cac tac » cac toc, cac bac, cac dac
ca tinh » cua tinh, cac tinh, va tinh
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
tac ca » tac cua, tac can, tac cay

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 cau hoi. hieu ve cac tac ca tinh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang cau hoi. hieu ve cac tac ca tinh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach ty)) nang cau hoi. hieu ve cac tac ca tinh tai cua tre*.