Perhaps you should try some spelling variations:
kho tang » cao tang
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
kem cua » em cua, keo cua, diem cua
hieu va » lieu va, hieu qua
tu sach » thu sach, te sach, tu cach
ky tang » ky nang, ky dang, ky trong
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ((ky tang) OR (kho tang)) ha noi. hieu va nam thuc vat hanh kem cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ((ky tang) OR (kho tang)) ha noi. hieu va nam thuc vat hanh kem cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ((ky tang) OR (kho tang)) ha noi. hieu va nam thuc vat hanh kem cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ((ky tang) OR (kho tang)) ha noi. hieu va nam thuc vat hanh kem cua tre*.