Perhaps you should try some spelling variations:
ban hanh » ban hang
vat hanh » vat thanh, van hanh, va hanh
cam thuc » am thuc, nam thuc, cam thu
so sach » so sanh, bo sach, co sach
doi cua » dai cua, hoi cua
hieu ve » hieu va, hieu van
ly hang » ly quang
ly vang » ly van, ly quang
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ly vang) OR (ly hang)) x ho. hieu ve cam thuc ((vat hanh) or (ban hanh)) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ly vang) OR (ly hang)) x ho. hieu ve cam thuc ((vat hanh) OR (ban hanh)) doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ly vang) OR (ly hang)) x ho. hieu ve cam thuc ((vat hanh) or (ban hanh)) doi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ly vang) OR (ly hang)) x ho. hieu ve cam thuc ((vat hanh) or (ban hanh)) doi cua tre*.