Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
hanh dai » hanh tai, hanh dao, vanh dai
su sach » so sach
vu sach » vu bach, vu khach
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho
o hoc » co hoc, mo hoc, so hoc
va am » va lam, va cam
thuc » thu

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) or (vu sach)) y nang ((x hoi) or (o hoc)). hieu va am thuc vat hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) y nang ((x hoi) OR (o hoc)). hieu va am thuc vat hanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) y nang ((x hoi) or (o hoc)). hieu va am thuc vat hanh dai cua tre*.