Perhaps you should try some spelling variations:
thuoc ma » hoc ma, duoc ma
hanh lai » hanh lam, hanh tai, thanh lap
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
va bac » van bac, va cac, va bai
x hoi » xa hoi, o hoi, 5 hoi

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (x ho)). hieu va bac ((thuoc ma) OR (thuc va)) hanh lai cua tre~.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) or (x ho)). hieu va bac ((thuoc ma) or (thuc va)) hanh lai cua tre*.