Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
day nhanh » day thanh, duy nhanh, dac nhan
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
day hanh » day thanh, dao hanh, day manh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
le cua » ly cua
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: su sach ky nang x hoi. hieu van cham thuc ((day hanh) or (day nhanh)) le cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang x hoi. hieu van cham thuc ((day hanh) OR (day nhanh)) le cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. hieu van cham thuc ((day hanh) or (day nhanh)) le cua tre*.