Perhaps you should try some spelling variations:
sach kem » hanh kem
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
hang dau » hang va, hang tai
tai cua » thai cua, tai cuc, tri cua
xuc van » duc van, luc van, vuc van
cua tre » cua te, cuu tre, cua triet
dau hoi » cau hoi, dai hoi, dan hoi
sach ty » sach y, sach tu, sach thu
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai

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 kem) or (sach ty)) hang dau hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach kem) OR (sach ty)) hang dau hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach kem) or (sach ty)) hang dau hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach kem) or (sach ty)) hang dau hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh tai cua tre*.