Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
cham thuc » nham thuc, pham thuc, tham thuc
ban hanh » ban hang
so sach » so sanh, bo sach, co sach
sach ly » sach y, sach lo, sach ty
ly vang » ly hang, ly van, ly quang
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
vang x » nang x

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 x ho. hieu ve cham thuc ((vat thanh) or (ban hanh)) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ly vang x ho. hieu ve cham thuc ((vat thanh) OR (ban hanh)) doi cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach ly vang x ho. hieu ve cham thuc ((vat thanh) or (ban hanh)) doi cua tre*.