Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
day nhanh » duy nhanh, dac nhan, day manh
day thanh » dao thanh, dat thanh, da thanh
sach ky » sac ky, sach y, sach ty
vu sach » vu bach, su sach, vu khach
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua
o hoc » co hoc, mo hoc, so hoc
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang ((x hoi) or (o hoc)). hieu ve cham thuc ((day thanh) or (day nhanh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ((x hoi) OR (o hoc)). hieu ve cham thuc ((day thanh) OR (day nhanh)) di cua tre.
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ((x hoi) or (o hoc)). hieu ve cham thuc ((day thanh) or (day nhanh)) di cua tre*.