Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
cam thuc » am thuc, nam thuc, cam thu
ban hanh » ban hang
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ve cam » ve cham, ve cac, va cam
x hoi » xa hoi, o hoi, 5 hoi

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 y nang ((x hoi) or (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: su sach y nang ((x hoi) OR (x ho)). hieu ve cam thuc ((vat hanh) OR (ban hanh)) doi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach y nang ((x hoi) or (x ho)). hieu ve cam thuc ((vat hanh) or (ban hanh)) doi cua tre*.